Climate Change Blogs

California Drought/Polar Vortex Jet Stream Pattern Linked to Global Warming

Published: 16 avril 2014
From November 2013 - January 2014, a remarkably extreme jet stream pattern set up over North America, bringing the infamous "Polar Vortex" of cold air to the Midwest and Eastern U.S., and a "Ridiculously Resilient Ridge" of high pressure over California, which brought the worst winter drought conditions ever recorded to that state. A new study published this week in Geophysical Research Letters, led by Utah State scientist S.-Y. Simon Wang, found that this jet stream pattern was the most extreme on record, and likely could not have grown so extreme without the influence of human-caused global warming. The study concluded, “there is a traceable anthropogenic warming footprint in the enormous intensity of the anomalous ridge during winter 2013-14, the associated drought and its intensity."

Figure 1. An extreme jet stream patten observed at 00 UTC on January 16, 2014. Color-coded wind speeds at a pressure of 300 mb (roughly 9,000 meters or 30,000 feet) show the axis of the jet stream over North America, with a large upside-down "U"-shaped ridge of high pressure over the West Coast. California is outlined in orange. The strongest winds of the jet stream (orange colors, 160 mph) were observed over the Northeast United States, where a strong "U"-shaped trough of low pressure was anchored. Image generated from the 00 UTC January 16, 2014 run of the GFS model, and plotted using our wundermap.

Using observations and a climate model to diagnose the human contribution to the jet stream pattern
The researchers studied the historical pressure patterns for November - January over North America during the period 1960 - 2014, and found that a strong "dipole" pattern of high pressure over Western North America and low pressure over Eastern North America, such as occurred during the winter of 2013 - 2014, tended to occur naturally during the winter immediately preceding an El Niño event. Since NOAA is giving a greater than 50% of an El Niño event occurring later in 2014, this past winter's dipole pattern may have been a natural expression of the evolving progression towards El Niño. The study also found that the dipole pattern could be intensified by two other natural resonances in the climate system: the Arctic Oscillation, and a variation of ocean temperatures and winds in the Western North Pacific called the Western North Pacific (WNP) pattern. But the dipole of high pressure over California combined with the "Polar Vortex" low pressure trough over Eastern North America during November 2013 - January 2014 was of unprecedented intensity, and extremes in this dipole pattern--both in the positive and negative sense--have been increasing since 2000 (the peak negative value occurred during the winter of 2009 - 2010.) The researchers used a climate model to look at whether human-caused climate change might be interfering with the natural pattern to cause this unusual behavior. They ran their climate model both with and without the human-caused change to the base state of the climate included, and found that they could not reproduce the increase in amplitude of the dipole pattern unless human-caused global warming was included. They concluded, "It is important to note that the dipole is projected to intensify, which implies that the periodic and inevitable droughts California will experience will exhibit more severity. The inference from this study is that the abnormal intensity of the winter ridge is traceable to human-induced warming but, more importantly, its development is potentially predicable." In an email to me, the lead author of the study, Simon Wang, emphasized that the opposite sign of the dipole--an extreme trough of low pressure over Western North American, combined with an extreme ridge of high pressure over Eastern North America--is also expected to be more intense when it occurs, leading to an increase in extremely wet winters in California.

Dr. Joe Romm's post on the study, "Bombshell: Study Ties Epic California Drought, ‘Frigid East’ To Manmade Climate Change", has this quote by climate scientist Michael Mann on the new research:

We know that human-caused climate change has played a hand in the increases in many types of extreme weather impacting the U.S., including the more pronounced heat waves and droughts of recent summers, more devastating hurricanes and superstorms, and more widespread and intense wildfires.

This latest paper adds to the weight of evidence that climate change may be impacting weather in the U.S. in a more subtle way, altering the configuration of the jet stream in a way that disrupts patterns of rainfall and drought, in this case creating an unusually strong atmospheric “ridge” that pushed the jet stream to the north this winter along the west coast, yielding record drought in California, flooding in Washington State, and abnormal warmth in Alaska. The recent IPCC assessment downplays these sorts of connections, making it very conservative in its assessment of risk, and reminding us that uncertainty in the science seems to be cutting against us, not for us. It is a reason for action rather than inaction.

Figure 2. One of the key water supply reservoirs for Central California, Lake Oroville, as seen on January 20, 2014. Thanks to an unusually intense ridge of high pressure over Western North America, California endured its driest November - January period on record this past winter, resulting in the worst winter drought on record. Image credit: California Department of Water Resources.

Other research connecting extreme circulation patterns to human causes
This week's paper by Dr. Wang is the second he has authored which has found a human fingerprint on extreme atmospheric circulation patterns. His 2013 paper, "Identification of extreme precipitation threat across midlatitude regions based on short-wave circulations," discussed how there's been a trend during the period 1979 - 2010 towards a pronounced circulation shift involving the low-level jet stream (LLJ), which is capable of bringing more extreme precipitation events (and droughts) to the mid-latitudes. Using four different climate models, the study found that the circulation shift only occurs when one runs climate models with the effects of human-caused emissions of greenhouse gases like carbon dioxide included; "control" runs of these models using only natural changes to the climate could not reproduce the observed increase in this more extreme circulation pattern. The paper concluded that several recent extreme precipitation events, including those leading to the 2008 Midwest flood in U.S., the 2011 tornado outbreaks in southeastern U.S., the 2010 Queensland flood in northeastern Australia, and to the opposite sense, the 2012 central U.S. drought, could have been influenced by human-caused changes to the atmospheric circulation. The fact that his research helps us understand how human-caused climate change is contributing to higher amplitude jet stream patterns should make them more predictable, potentially saving lives and money.

Wang, S, Davies, R.E., and R.R. Gillies, 2013, "Identification of extreme precipitation threat across midlatitude regions based on short-wave circulations," J. Geophys. Res. Atmos., 118, 11,059–11,074, doi:10.1002/jgrd.50841.

Wang, S., Hipps, L., Gillies, R.R., and J.-H. Yoon, 2014, "Probable causes of the abnormal ridge accompanying the 2013-14 California drought: ENSO precursor and anthropogenic warming footprint", Geophysical Research Letters, DOI: 10.1002/2014GL059748. News Release.

Related information
There is an growing body of research exploring connections between human-caused climate change and the increase in unusual jet stream patterns we've seen in recent years. Most of this research focuses on potential linkages between Arctic warming and atmospheric circulation patterns. Below are links to wunderground blog posts on the subject, and to the original research studies and associated press releases.

"The Changing Face of Mother Nature", wunderground guest post by Dr. Jennifer Francis of Rutgers, April 22, 2013.

Extreme jet stream causing record warmth in the east, record cold in the west (January 2013)

Arctic sea ice loss tied to unusual jet stream patterns (April 2012)

Our extreme weather: Arctic changes to blame? (December 2011)

Florida shivers; Hot Arctic-Cold Continents pattern is back (December 2010)

Jet stream moved northwards 270 miles in 22 years; climate change to blame? (June 2008)

Dr. Ricky Rood has done a whole series of posts on climate change and the Arctic Oscillation, including:

Cold Weather in Denver: Climate Change and Arctic Oscillation (8)

Are the changes in the Arctic messing with our weather? The Future of Blocking

Papers linking Arctic warming to an increase in negative AO/NAO conditions
Deser, C., R. Tomas, M. Alexander, and D. Lawrence, 2010, "The seasonal atmospheric response to projected Arctic sea ice loss in the late 21st century," J. Clim., 23, 333–351, doi:10.1175/2009JCLI3053.1.

Francis, J.A., and S.J. Vavrus (2012), "Evidence linking Arctic amplification to extreme weather in mid-latitudes," Geophysical Research Letters, 21 February, 2012. Accompanying article at the Yale Forum on Climate Change, Linking Weird Weather to Rapid Warming of the Arctic.

Francis, J. A., W. Chan, D. J. Leathers, J. R. Miller, and D. E. Veron, 2009, "Winter northern hemisphere weather patterns remember summer Arctic sea-ice extent," Geophys. Res. Lett., 36, L07503, doi:10.1029/2009GL037274.

Honda, M., J. Inoue, and S. Yamane, 2009, "Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters," Geophys. Res. Lett., 36, L08707, doi:10.1029/2008GL037079.

Jaiser, R., K. Dethloff, D. Handorf, A. Rinke, J. Cohen (2012), "Impact of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation", Tellus A 2012, 64, 11595, DOI: 10.3402/tellusa.v64i0.11595

Liu et al. (2012), "Impact of declining Arctic sea ice on winter snowfall", Proc. Natl. Academy of Sciences, Published online before print February 27, 2012, doi: 10.1073/pnas.1114910109. Accompanying press release. My blog post.

Overland, J. E., and M. Wang, 2010, "Large-scale atmospheric circulation changes associated with the recent loss of Arctic sea ice," Tellus, 62A, 1.9.

Petoukhov, V., and V. Semenov, 2010, "A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents," J. Geophys. Res.-Atmos., ISSN 0148-0227.

Seager, R., Y. Kushnir, J. Nakamura, M. Ting, and N. Naik (2010), "Northern Hemisphere winter snow anomalies: ENSO, NAO and the winter of 2009/10," Geophys. Res. Lett., 37, L14703, doi:10.1029/2010GL043830.

Seierstad, I. A., and J. Bader (2009), "Impact of a projected future Arctic Sea Ice reduction on extratropical storminess and the NAO," Clim. Dyn., 33, 937-943, doi:10.1007/s00382-008-0463-x.

Tang et al., "Cold winter extremes in northern continents linked to Arctic sea ice loss," Environ. Res. Lett. 8 014036 doi:10.1088/1748-9326/8/1/014036. My April 2013 blog post.

Papers linking Arctic warming to Western U.S. drought
Sewall, Jacob O., 2005, Precipitation Shifts over Western North America as a Result of Declining Arctic Sea Ice Cover: The Coupled System Response, Earth Interact., 9, 1–23. doi:

Sewall, J.O., and L.C. Sloan, 2004, Disappearing Arctic sea ice reduces available water in the American west, Geophys. Res. Lett., 31, L06209, doi:10.1029/2003GL019133. Accompanying news release.

Papers linking Arctic sea ice loss to changes in summer rainfall
Li Y, LR Leung, Z Xiao, M Wei, and Q Li. 2013, Interdecadal Connection between Arctic Temperature and Summer Precipitation over the Yangtze River Valley in the CMIP5 Historical Simulations, Journal of Climate 26(19):7464-7488. DOI: 10.1175/JCLI-D-12-00776.1 Accompanying press release.

Li, Y, and L.R. Leung, 2013, "Potential Impacts of the Arctic on Interannual and Interdecadal Summer Precipitation in China", Journal of Climate 26(3):899-917. DOI: 101175/JCLI-D-12-00075.1

Screen, J.A., 2013, "Influence of Arctic sea ice on European summer precipitation", Environ. Res. Lett. 8 044015 doi:10.1088/1748-9326/8/4/044015. Accompanying press release.

Wu, B., Zhang R, D’Arrigo. R., and J. Su, 2013, "On the relationship between winter sea ice and summer atmospheric circulation over Eurasia," J. Clim. 26 5523–36

Papers exploring the link between Arctic warming to changes in large-scale atmospheric circulation
Cassano, E.N., Cassano, J.J, Higgins, M.E., and M.C. Serreze, 2013, "Atmospheric impacts of an Arctic sea ice minimum as seen in the Community Atmosphere Model", Int. J. Climatol., in press. (doi:10.1002/joc.3723)

Overland, J.E., Francis, J.A., Hanna, E., and M. Wang, 2012, "The recent shift in early summer Arctic atmospheric circulation," Geophys. Res. Lett. 39 L19804, DOI: 10.1029/2012GL053268

Petoukhov, V., Rahmstorf, S., Petri, S., Schellnhuber, H. J. (2013), "Quasi-resonant amplification of planetary waves and recent Northern Hemisphere weather extremes" Proceedings of the National Academy of Sciences, (Early Edition) [doi:10.1073/pnas.1222000110]. Easy-to-read description of the paper by the authors, published at Accompanying press release. My March 2013 blog post.

Screen, J.A., and I. Simmonds, 2013, "Exploring links between Arctic amplification and mid-latitude weather", Geophys. Res. Lett. 40 959–64.

Jeff Masters

IPCC: Cost of Avoiding Dangerous Climate Change Super-Affordable if We Act Now

Published: 13 avril 2014
Climate change is a huge threat to civilization if we do nothing more to reduce it, but the costs are very affordable if we start now, said the Nobel-prize winning Intergovernmental Panel on Climate Change (IPCC) today, in the third installment of their once-every-seven-years report on the climate. Today's report on mitigation--how we can slow down climate change--was the most hopeful of the reports, since it found that the cost of keeping global warming under the "dangerous" level of 2°C will only reduce "consumption growth" of the global economy by 0.06% per year if we start immediately and act strongly. Since consumption growth is expected to increase between 1.6% and 3% per year in the coming decades, we’re talking about annual growth that is, for example, 2% rather than 2.06%. This is a small price to pay to greatly decrease the risks of increased hunger, thirst, disease, refugees, and war outlined in the IPCC's frightening Working Group 2 report on risks and adaptation released two weeks ago. Today's report was authored by 235 scientists from 58 countries, and was approved by the governments of every nation of the world who cared to send a representative to the week-long approval meeting in Berlin, Germany. There is one more portion of the 2013 - 2014 IPCC report coming, a grand summary of Parts 1, 2, and 3 that will be released around November 1, 2014. Some key themes from today's report on mitigation:

Emissions of greenhouse gases are rising at a near-record pace. Greenhouse gas emissions grew 2.2% per year between 2000 - 2010, compared to a rate of 1.3% per year between 1979 - 2000. The increase was 3% per year between 2010 - 2011, and 1 - 2% from 2011 - 2012. About 76% of the greenhouse gases emitted were in the form of CO2, with 16% from methane. In 2010, ten countries accounted for about 70% of the world's CO2 emissions from fossil fuels and industrial processes. About half of the cumulative human-caused CO2 emissions between 1750 and 2010 have occurred in the last 40 years.

If we are going to avoid a dangerous 2°C (3.6°F) warming, we must make large and rapid cuts in greenhouse gas emissions. At the 2010 climate talks in Cancun, the governments of the world agreed that global warming should be kept under 2°C (3.6°F) above pre-industrial levels in order to avoid a "dangerous" threshold of climate change. The new IPCC report says that in order to do this, the share of zero and low carbon energy sources like solar, wind, nuclear, and unproven technologies like fossil fuel with Carbon Capture and Storage (CCS) must at least triple by 2050, and greenhouse gas emissions will have to fall 40 - 70%, compared to 2010 levels. By 2100, emissions of CO2 need to be near zero. This would require about $30 billion per year less to be spent on fossil fuels from 2010 - 2029, $147 billion per year more to be spent on zero and low carbon energy sources, and several hundred billion per year more per year to be spent on energy efficiency. (For comparison, the annual global total investment in the energy system is $1.2 trillion.) The report emphasizes that the greenhouse gas reduction promises made at the 2010 Cancun summit for the year 2020 are not enough to keep warming of the planet below 2°C at the lowest cost, though will likely keep a 3°C temperature rise from occurring.

If the world delays mitigation through 2030, it will be much more expensive and perhaps impossible to keep warming below 2° C. Models that delayed doing significant emission cuts until 2030 showed that the economic costs during the transition to renewable energy and in the long-term would be higher. Also, if some key (and unproven) technologies such as Carbon Capture and Storage (CCS) and Bio-Energy with Carbon Capture and Storage (BECCS) turn out not to be feasible at large scales, it will be difficult to keep warming below 2° C.

Keeping Earth's temperature rise below 2°C will have additional co-benefits. For example:
1) Reducing air pollution. The World Health Organization reported that in 2012 about 7 million people died--one in eight of total global deaths--as a result of air pollution exposure.
2) Improving energy security, leading to less price volatility and fewer supply disruptions.
3) Environmental protection.

There is a huge opportunity in the next few decades to build low-emission cities. Urban land cover is projected to expand by 56 - 310% between 2000 and 2030. Most of this urban infrastructure has yet to be built, presenting a tremendous opportunity to build the new urban areas so they emit fewer greenhouse gases. However, this will require strong policy, technical, financial and institutional measures.

Economic and population growth are the main drivers of greenhouse gas emissions. We've grown far more efficient at producing goods using less energy, meaning that the "energy intensity" of the global economy steadily declined from 2000 - 2010. However, increasing economic growth and population growth have outpaced the decline in energy intensity, resulting in higher greenhouse gas emissions. "Without additional efforts to reduce GHG emissions beyond those in place today, emissions growth is expected to persist driven by growth in global population and economic activities." If we take no additional measures to slow down human-caused climate change, the planet is expected to warm by about 4°C by 2100 compared to per-industrial levels. That's the same difference in temperature as between today's climate and the Ice Age.

Greenhouse gas emissions from deforestation are decreasing. Some good news is that the global rate of deforestation has been going down, which has made greenhouse gas emissions due to land use changes decline (greenhouse gas emissions due from agriculture, forestry, and other land use are 24% of the human total.) These type of emissions are projected to continue to fall, and possibly go to zero by 2100.

Renewable energy is growing fast, but needs help to increase its market share. In order to help renewable energy grow more rapidly, direct or indirect subsidies are needed. Indirect subsidies could occur by taxing fossil fuels or adopting a cap and trade system. The report doesn't recommend any particular policy actions, but does note that "to help reduce possible adverse effects on lower income groups who often spend a large fraction of their income on energy services, many governments have utilized lump‐sum cash transfers or other mechanisms targeted on the poor."

New Blockbuster IPCC Climate Report: Comprehensive, Authoritative, Conservative, my September 2013 post on who the IPCC is, and how they write their reports.

Landmark 2013 IPCC Report: 95% Chance Most of Global Warming is Human-Caused, my September 2013 post on Part I of the 2013 - 2014 IPCC report.

IPCC: Climate Change Increasing Risk of Hunger, Thirst, Disease, Refugees, and War, my March 31, 2014 post on Part II of the 2013 - 2014 IPCC report.

Available: professionals willing to speak about climate change to local groups
If your school, chamber of commerce, church, library, or community club needs a local expert on climate science to come speak, the University Corporation for Atmospheric Research (UCAR) and the United Nations Foundation can help out, thanks to a new effort called The organization has more than 160 volunteer experts from al 50 states in a database that is searchable by geographic location, expertise, and languages spoken. If you are have expertise in climate science and are interested in volunteering for this network, please go to and create a profile. I have my own set of slides I use for such talks that anyone is welcome to borrow from, available at

Jeff Masters
Categories:Climate Change

Energy, Food, Population and Climate

Published: 9 avril 2014
Energy, Food, Population and Climate

I was reading this article, Green Energy Draws Investment Worldwide, which reports on the United Nations' Global Trends in Renewable Energy Investments 2014. The article documents that global investments in renewable energy dropped in 2013, but also notes that China now exceeds Europe in renewable energy investments. Part of the reason for reduced investment in renewable energy was due to the declining price of solar energy. Another reason is unstable energy policy. In the U.S., for instance, the investment in wind energy jumps up and down based on incentives such as tax credits. The amount of energy produced by renewables continues to increase from year to year. If we obtained this energy from fossil fuels, there would be approximately 20% more carbon dioxide emissions.

Even with accounting that carbon dioxide emissions are only 80% of what they might be, the total global emissions of carbon dioxide continue to increase every year. Here is a figure put together from reports from the International Energy Agency.

Figure 1: World Primary Energy Supply in 1973 and 2003. From International Energy Agency.

In 1973 oil provided 45.0 % of the world’s energy and in 2003 the number is 34.4%. Natural gas provided 16.2% in 1973 and 21.2% in 2003. Coal was 24.8% in 1973 and 24.4% in 2003. If I add correctly in 1973 fossil fuels provided 86% of the world’s energy and in 2003 fossil fuels provided 80% of our energy. The big difference between 1973 and 2003 was the increase in nuclear.

The emissions continue to increase because the total amount of energy generated increased. Mtoe is Megatons oil equivalent, and that number went from about 6,000 to 10600 in 30 years. In that 30-year period there was about a 75% increase in total energy production.

Figure 2 shows in the top part of the figure the same type of information as in the above figure, but for 2011. Total energy production in 2011 was about 13,113 Megaton oil equivalent. In 2011, the increase in energy production is approximately 120% compared to 1973. Compared to 2003, the 2011 energy production is about 25% higher.

Figure 2: World Primary Energy Supply in 2011, top. From International Energy Agency. Total energy production in 2011 was about 13,113 Megaton oil equivalent. The bottom part of the figure is the percentage of carbon dioxide emissions from each energy type.

When we look at the percentage of energy production, the energy coming from non-fossil fuel sources is 18%. Percentage wise, the amount that might be accounted to renewables has actually decreased. Therefore, we do have less carbon dioxide emissions than might be the case, but our energy use increases and our reliance on fossil fuels remains in many ways the same. The amount of energy produced by non-fossil fuels today would have been over 40% of the world’s energy use in 1973.

In terms of share of energy production, coal has increased at the expense of both oil and non-fossil fuels. If you look at the bottom part of the figure, the high amount of carbon dioxide emissions from coal shows that coal is especially bad for the climate.

In the past decade, globally, coal has grown more than either renewables or natural gas. This has fueled, especially, the economies of India and China, leading to a significant rise in standard of living. This shows up as large changes in, for example, hunger statistics. The tie between economic success, energy use and carbon dioxide becomes more clear. Despite amazing growth in the use of renewables, which has actually decreased carbon dioxide emissions in Europe, the total growth in energy production overwhelms this decrease. This makes the current continued increase in carbon dioxide emissions more staggering – it comes in the presence of real reductions in emissions from renewables.

The increase in energy production improves economies. Bringing economic development to a larger percentage of the world’s population, while the population continues to grow, assures decades more of very high emissions. If we then make the reach that economic growth and standard of living are accompanied by consumption of more meat, which has always been the case, we see an amplifying impact on emissions coming from agriculture.

We are therefore even in the best of cases committed to further increases in carbon dioxide emissions, as well as emissions of other greenhouse gases. The ultimate way to limit warming is to reduce emissions, which requires energy sources and food supplies that do not emit greenhouse gases. At this point we are not even offsetting the increase of carbon dioxide emissions by our adoption of renewables. It is interesting to note that China, now the world’s largest emitter, is also the world’s largest investor in renewable energy. Also noteworthy, is that China has driven down the price of solar energy. This places China in not only a potential technological advantage, but is also building policy advantage, as China is on a path that might displace coal’s role in energy production.


IPCC: Climate Change Increasing Risk of Hunger, Thirst, Disease, Refugees, and War

Published: 31 Mars 2014
Climate change is already having "widespread impacts", and has the potential to worsen global hunger, water availability, disease, drought, flooding, refugees, and war in the coming decades if we do nothing to reduce it, said the Intergovernmental Panel on Climate Change (IPCC) today, in the latest installment of their once-every-seven-year report on the climate. Today's report on climate change impacts and how we can adapt to them warned that "throughout the 21st century, climate-change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security, and prolong existing and create new poverty traps." Today's report by the Nobel-prize winning group of scientists was the second of four parts. Part 1, released in September 2013, covered the physical science behind climate change. Part 3 (due out in mid-April, 2014) will discuss how we can mitigate (reduce) climate change impacts. Part 4 (due out in early November, 2014) will present a grand summary of Parts 1, 2, and 3. Some key themes from today's report:

Food supplies will tighten. To me, the most important finding of the report is the climate change's threat to reduce global food supplies, which have already been negatively impacted, and are at risk to get much worse: “Based on many studies covering a wide range of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts. Climate change has negatively affected wheat and maize (corn) yields for many regions and in the global aggregate." For the future, the report acknowledges that some areas will likely see increases in food production, due to increased CO2 in the air and more favorable precipitation, but the overall global trend in food supplies will likely be downward (Figure 1.) This downward trend in yields will occur in the face of rapidly increasing demand, as the population grows by 2 billion, resulting in "increased likelihood of under-nutrition resulting from diminished food production in poor regions."

Figure 1. Summary of projected changes in crop yields, due to climate change over the 21st century. The figure includes projections for different emission scenarios, for tropical and temperate regions, and for adaptation and no-adaptation cases combined. Over the period 2010 - 2029, about as many scenarios predict an increase in global crop yields as predict a decrease. However, beyond 2030, more than twice as many scenarios predict a decrease versus an increase. Relatively few studies have considered impacts on cropping systems for scenarios where global mean temperatures increase by 4°C or more. For five time frames in the near-term and long-term, data (n=1090) are plotted in the 20-year period on the horizontal axis that includes the midpoint of each future projection period. Changes in crop yields are relative to late-20th-century levels. Data for each time frame sum to 100%. Image credit: IPCC.

Water availability to people will decrease, as wet areas get wetter and dry areas get drier. Not only does climate change pose huge risks to our food supply, it also threatens water availability. “The fraction of global population experiencing water scarcity and the fraction affected by major river floods increase with the level of warming in the 21st century.”

We're not adapting fast enough to avoid serious damage. The report talks about "adaptation deficits", as demonstrated by our relatively poor ability to respond to impacts from from recent extreme climatic events. "Climate-change-related risks from extreme events, such as heat waves, extreme precipitation, and coastal flooding, are already moderate (high confidence) and high with 1°C additional warming (medium confidence)." IPCC author and Princeton Professor Michael Oppenheimer put it more succinctly to the Associated Press: “We’re all sitting ducks.”

Poor people are most at risk from climate change. Climate-related hazards constitute an additional burden to people living in poverty, acting as a threat multiplier.

Climate change increases the risk of violence. For the first time, the IPCC lays out the case that climate change can add a destabilizing factor that can make violence more likely in countries with social and economic inequalities. "Climate change can indirectly increase risks of violent conflicts in the form of civil war and inter-group violence by amplifying well-documented drivers of these conflicts such as poverty and economic shocks."

Climate change increases the risk of more refugees. "Displacement risk increases when populations that lack the resources for planned migration experience higher exposure to extreme weather events."

Climate change will be costly. Though the uncertainties are high, the costs for an additional 2°C rise in temperature are thought to be between 0.2 and 2.0% of global GDP. "Losses are more likely than not to be greater, rather than smaller, than this range, since it is difficult to account for catastrophic changes, tipping points, and many other factors."

Human health will suffer. "Throughout the 21st century, climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income…the magnitude and severity of negative impacts are projected to increasingly outweigh positive impacts. Examples include greater likelihood of injury, disease, and death due to more intense heat waves and fires; increased likelihood of under-nutrition resulting from diminished food production in poor regions; risks from lost work capacity and reduced labor productivity in vulnerable populations; and increased risks from food- and water-borne diseases and vector-borne diseases" (like malaria.)

We can take action to reduce these substantial risks. "Mitigation is considered essential for managing the risks of climate change." Mitigation refers to human actions to reduce climate change. Burning fewer fossil fuels and thus putting less CO2 in the air is essential to mitigating climate change. We should view the next few decades as the era of ‘climate responsibility’, when we can make a huge difference to keep our future climate livable. The report emphasizes that if greenhouse gases continue to rise, the world can expect an additional 6 - 7°F (3.5 - 4°C) of warming by 2100, instead of the international goal of keeping this rise less than 2°F (1.2°C). Princeton's Dr. Oppenheimer compared these two choices as "the difference between driving on an icy road at 30 mph versus 90 mph. It's risky at 30, but deadly at 90." Uncertainty is not a reason to delay climate action, and it is cheaper to act now on climate change than to delay. The International Energy Agency said in 2013 that in order to keep global warming less than 2°C above pre-industrial levels, "Delaying stronger climate action until 2020 would avoid $1.5 trillion in low-carbon investments up to that point, but an additional $5 trillion would then need to be invested through to 2035 to get back on track." The latest IPCC findings will be a key discussion topic for world leaders at a September 23, 2014 Climate Summit in New York City, hosted by UN Secretary-General Ban Ki-moon. The summit aims to mobilize political will to pave the way for an ambitious global legal climate agreement to be signed at the critical December 2015 Conference of Parties (COP) negotiations in Paris.

Associated Press coverage of the IPCC Part 2 report.

New Blockbuster IPCC Climate Report: Comprehensive, Authoritative, Conservative, my September 2013 post on who the IPCC is, and how they write their reports.

Landmark 2013 IPCC Report: 95% Chance Most of Global Warming is Human-Caused, my September 2013 post on Part I of the 2013 - 2014 IPCC report.

Video 1. The IPCC released this video to accompany today's release of their 2014 Impacts and Adaptation report.

Jeff Masters
Categories:Climate Change

Save the Keeling Curve!

Published: 11 Mars 2014
Climate change's most iconic research project is in danger--a victim of budget cuts in an era of increased government belt-tightening. The Keeling Curve is a measurement of the concentration of carbon dioxide in the atmosphere made atop Hawaii’s Mauna Loa, begun in 1958 by Dr. Charles Keeling. It is the longest-running such measurement in the world. The curve was instrumental in showing how human emissions of carbon dioxide were steadily accumulating in Earth's atmosphere, and raised awareness that human-caused climate change was an ever-increasing threat to the stability of our climate. After Keeling's death in 2005, the measurements were continued by his son, Ralph F. Keeling. Support from NSF, NOAA and NASA is being diminished or withdrawn, and Keeling has turned to crowd-funding to help raise funds to continue these important measurements. I hope you can join me in making a donation.

Figure 1. The Keeling Curve: climate change's most iconic image. The curve's steady year-by-year increase in CO2 due to burning of coal, oil, and natural gas has wriggles on top of it, due to the natural seasonal cycle in CO2--plants suck in CO2 during the Northern Hemisphere growing season, then release it during the winter. Image credit: Scripps Institution of Oceanography, USCD.

Figure 2. Dr. Charles Keeling posing at the entrance to the Charles Keeling Building at Mauna Loa, Hawaii. Image credit: NOAA/ESRL.

CO2 Levels Hit 401 ppm
The latest data from the Keeling curve website shows that atmospheric carbon dioxide levels are surging upwards in their usual late winter push, as plants return CO2 to the atmosphere before the Northern Hemisphere spring growing season hits. CO2 levels reached 401 ppm (parts per million) last week on top of Mauna Loa, setting a new record. CO2 levels were at 280 ppm in 1870, increased less than 1 ppm per year in the 1960s, then accelerated to 2 ppm per year during the 2000s. Less than 1% of the increase since 1870 has been due to natural sources, such as volcanoes. The last time carbon dioxide levels reached 400 ppm—between 2.5 and 5 million years ago during the Pliocene Era—the Earth was 3.5 to 9° F warmer (2 to 5° C), and sea levels were 65 to 80 feet higher.

There is a hashtag #savetheKeelingCurve
Eli Rabett's post, Shaking the Cup for Science
What Does 400 ppm Look Like? December 2013 blog post by Robert Monroe of the Scripps Institution of Oceanography.

Senate holds all-nighter on climate change
A group of 31 U.S. Senators pulled an all-nighter last night on the floor of the U.S. Senate, taking turns from 9 pm Monday night until 9 am Tuesday morning to promote policy actions on climate change. Many of the Senators involved issued tweets using the hashtag #Up4Climate. The all-nighter was another indication that politicians are becoming increasingly bold about speaking up on climate change.

Latest Version of our WunderMap App Now Includes WunderPhotos
Weather Underground has released today a new version of our WunderMap app for iPhone and iPad. The main new feature that we'd like to highlight is the WunderPhotos layer--now users can view, share, and submit photos all from within the app. Here are a few of the features of the new version of the WunderMap app:

◦ Improved Weather Station display, and both station size and station spacing are now adjustable (Weather Stations Layer ⇒ Settings).
◦ New WunderPhotos layer! View, share, and submit beautiful weather photos.
◦ Fixed incorrect elevation for some Personal Weather Stations.
◦ Swipe-to-delete search history items.
◦ "Terrain/Satellite” and other map options made more prominent.
◦ Bug fixes (crashes, visual glitches, and usability enhancements).
◦ Optimized performance across all devices.

The latest version is available to download for iPhone and iPad at

Jeff Masters
Categories:Climate Change
About the Blogs
These blogs are a compilation of Dr. Jeff Masters,
Dr. Ricky Rood, and Angela Fritz on the topic of climate change, including science, events, politics and policy, and opinion.