Author Archives: Ilissa Ocko

How scientists linked the California drought to climate change

A drought-stricken vineyard in Napa Valley. Source: John Weiss/Flickr

California has officially entered its fourth consecutive year of drought, and is trapped in its worst water shortage situation ever.

Because we know that human-caused climate change cantrigger and exacerbate drought conditions, media, public officials, California residents and scientists have all been wondering for years if rising global temperatures likely caused or contributed to the current drought in California.

The short answer: Yes, they did.

Weather won’t cooperate

Scientists have suspected for some time now that a certain meteorological condition lies behind the long-lasting California drought. The persistence of a stubborn high-pressure system off the coast has been preventing storm systems from reaching California and instead deflecting them to Alaska and elsewhere.

While weather events are almost always multi-causal, the California drought is largely a result of this atmospheric weather pattern. The question is whether climate change has influenced the development, or sustenance, of this system.

Stanford scientists connected the dots

When destructive events happen, people want to know right then and there what’s going on— whether it’s an epidemic, riot or weather disaster.

But evaluating an extreme weather event for climate change influences is a scientific process that takes several months of computer simulations and statistical techniques. It can frustrate some who demand an answer right away.

Well, the results from several, month-long studies are finally in. Scientists from Stanford have found that the meteorological conditions that have caused the California drought are far more likely to occur in today’s warming world than in one without human-caused emissions of greenhouse gases.

It shows us – ironically and tragically – that the state thatleads the nation in curbing greenhouse gas emissions is right now suffering more than any other from climate change.

California is not alone

The California drought attribution studies are a subset of alarger collection of recently published studies that explain 16 extreme weather and climate events of 2013.

Twenty research teams explored the causes of events such as heat waves in Australia, New Zealand, Korea, Japan, China, and Europe; torrential downpours in Colorado and India, a blizzard in South Dakota, and a cold spell in the United Kingdom.

The studies overwhelmingly indicated that all heat waves were largely attributable to human-caused climate change. One study even suggested that the heat wave in Korea has been made 10 times more likely due to human influence.

The extreme rainfall events in India were concluded to have been more likely in a human-influenced world, but data for assessing precipitation events is rather limited as compared to heat waves. Further, studies concluded that the extreme rainfall event in Colorado, the blizzard in South Dakota, and the cold spell in the U.K. were unlikely to have been influenced by climate change.

Climate change is happening. Now.

So for anyone who may still think that the consequences of climate change are in the distant future, this collection of studies suggest that human-caused climate change is right now causing a crisis in America’s most populous state and the world’s eighth largest economy.

California reminds us that climate change is a major concern for societies everywhere, and that all nations are vulnerable to extreme weather events. It’s time we roll up our sleeves and stop this, once and for all.

This blog originally appeared on EDF Voices 

Posted in Basic Science of Global Warming| 4 Responses, comments now closed

Why California thirsts for rain and the East Coast gets soaked

Source: Flickr/Jared Tarbell

If you think the weather’s acting strange, you’re correct. Extreme weather in the United States is trending upward, and human-caused climate change has already been blamed for much of it – most recently in connection with theCalifornia drought.

But along with extreme weather we’re also getting extreme contrasts. What on Earth is going on when New York gets endless rain and San Francisco none, and when one part of the country is freezing while another suffers under record heat?

You guessed it, rising temperatures have something to do with it – and here’s how.

Rain patterns are changing

In the Northeast, the combination of more moisture in the atmosphere from a warmer world and changes in circulation patterns are bringing more rain. In the Southwest, meanwhile, rainfall is suppressed by a northward expansion of high pressure in the subtropics.

The crippling drought now plaguing California is due to a persistent high pressure system off of the coast that is deflecting storms away from the region. A recent study shows that these systems are much more likely to occur with human-caused climate change.

Rain is more intense

Heavy downpours are controlled by cloud mechanisms and moisture content, which are both changing as global temperatures rise. Clouds that can dump a lot of rain are more common in a warmer atmosphere.

More evaporation has led to more moisture in the atmosphere which, in turn, leads to more intense rainfall when it rains. That helps explain why the entire U.S. is experiencing more heavy downpours – even in the drought-stricken West.

Droughts are taking hold

Rain and evaporation will determine how moist the soil will be. So although evaporation is increasing nationwide due to warmer temperatures, higher precipitation in the Northeast yields a net increase in soil moisture in that part of the country.

In the Southwest, on the other hand, the drop in overall precipitation brings drier conditions that spawn or magnify drought. As the soil there dries out, the incoming sunlight will heat the ground instead of evaporating water from the soil. This creates a vicious cycle of more heat and less rain.

Flooding is more common

The potential for flooding, meanwhile, depends a lot on what's going on with the soil. The higher the soil moisture content, the higher the chance that there will be more runoff from rainfall.

Because soil moisture is increasing in the Northeast, flooding events are on the rise. Fortunately for the region, many heavy rain storms occur in the summer and fall when soil moisture is low and the ground can absorb more water.

On the other hand, the sea level has risen by a foot since the 1900s in the Northeast. That, in turn, contributes to more flooding.

Disaster costs are also rising – but there is hope

In 2013, intense storms, severe regional drought, and extreme flooding led to more than $9 billion in disaster costs in the U.S. alone. It’s uncertain what the total bill was if you factor in ongoing agriculture, human health and infrastructure losses from changing weather conditions

Unless we curb emissions of heat-trapping gases, scientists expect these trends to continue and worsen – and the contrast between wet and dry areas of the U.S. will likely become even sharper. Our hope now is that the push for climate action amps up so we can finally set ourselves on a better path for the future.

This post originally appeared on EDF Voices 

Posted in Basic Science of Global Warming, Greenhouse Gas Emissions, Science| 1 Response, comments now closed

Study: Climate change may push hurricanes farther north, south

A satellite image of Irene, a Category 1 hurricane, as it made landfall in North Carolina in August of 2011. Source: NASA/NOAA GOES project

The hurricane season of 2014 just kicked off, and with two devastating storms wreaking havoc along the northeastern United States coast over the last few years, it’s no wonder everyone’s on edge.

We’re concerned about hurricanes becoming more frequent and intense, and about the worsening storm surge caused by a rise in sea levels. But flying under the radar is a fourth link between hurricanes and climate change: how climate change affects the location of hurricanes.

new study led by researchers at the National Oceanic and Atmospheric Administration, the Massachusetts Institute of Technology and Princeton University found that hurricanes have been shifting pole-ward at a rate of 30 to 40 miles per decade over the last 30 years.

It means they are moving closer to major population centers such as Washington, New York and Boston.

The likely cause? Human-caused climate change.

The migration of hurricanes has “potentially profound consequences for life and property,” the authors of the study warn in an article published recently in the journal Nature.

Increasing hazard exposure and mortality risk from tropical cyclones may be compounded in coastal cities outside the tropics, while being offset at lower latitudes.”  

Linking climate change to hurricane location

This finding is an important advancement in scientists’ understanding of how climate change has already contributed to extreme weather events. Research shows that the rise in global temperatures already causes more warm days, heat waves, and heavy rainfall.

Detecting trends in hurricane activity has been difficult, however, due to inconsistent and often unreliable historical data.

To get around this data challenge, the scientists at NOAA, MIT and Princeton developed a new technique that relies on a dependable subset of the data, and which teases out natural events such as El Niño to detect a distinct relationship between hurricane activity and climate change.

Their conclusion: Hurricanes are drifting toward the poles most likely due to an expansion of the Hadley Cell, a permanent atmospheric circulation feature that carries heat from the tropics to the Earth’s temperate zones.

Scientific understanding is that the Hadley Cell expansion is a result of the increase in heat-trapping gases in the atmosphere from human activities. So as we continue to drive cars, generate electricity at fossil-fueled power plants, cut down trees, and farm – we are indirectly pushing hurricanes farther north and south.

The new study is groundbreaking not only because it uses a novel technique, but also because it links a hurricane trend to climate change.

What we know so far

So where are we today with hurricanes and climate change?

Scientists studying hurricanes:

  • Have found no observed trend in frequency
  • Have not been able to detect trends in intensity  and duration
  • Are confident that human-caused sea level rise is contributing to storm surge
  • Expect the frequency of intense storms to increase in the future
  • Have now detected a robust trend in location shifts that is likely due to human activity

This new research presented in Nature suggests that hurricanes are migrating toward the poles and may devastate densely populated coastal regions that had previously, for the most part, been spared such storms.

It’s yet another reason why we must act now to curb carbon pollution and limit climate change.

This post first appeared on EDF Voices

Posted in Basic Science of Global Warming, Clean Power Plan, Extreme Weather, Greenhouse Gas Emissions| 2 Responses, comments now closed

New report: How climate change is impacting where you live

The National Climate Assessment (NCA) report, prepared by the U.S. Global Change Research Program, is essentially the U.S. equivalent of the Intergovernmental Panel on Climate Change (IPCC): Using the best available science, over 300 experts synthesized current understanding of observed and future climate changes and impacts, particularly in the U.S. The third ever NCA was released today, and concludes beyond a reasonable scientific doubt that Americans are being affected by climate change.

Among the findings:

  • U.S. average temperatures have increased by 1.3 to 1.9ºF since record-keeping began in 1895, and most of this warming has occurred since 1970
  • Heavy precipitation has increased in many parts of the country
  • Extremes such as heat waves, droughts, floods, and North Atlantic hurricanes are more frequent and/or intense
  • Summer sea ice in the Arctic has halved since record-keeping began in 1979
  • Sea level rise has increased coastal erosion and storm surge damage

These changing conditions produce a variety of tangible stresses on society by affecting human health, water resources, agriculture, energy, infrastructure, and natural ecosystems. The particular impacts vary by region, but no corner of the country is immune to the change.

So what’s happening where you live?

Source: National Climate Assessment

Unless we take immediate action to curb our emissions of heat-trapping gases, the foreseeable future will be plagued by further warming and worsening impacts. The good news is that because we know what the cause is, we also know what is needed in order to stabilize our planet. We must come together now—locally, nationally, and internationally—and work towards a better future.

This post first appeared on our EDF Voices blog

Posted in Arctic & Antarctic, Basic Science of Global Warming, Extreme Weather, Oceans, Science| Comments closed

Top takeaways from the latest IPCC report

(This post originally appeared on EDF Voices)

Yesterday, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) released its last report in a three-part series that makes up the fifth assessment report (AR5) on the latest data and research on climate change. The reports have been issued approximately every five years since 1990.

This latest round of reports began in September 2013 with anupdate on the latest science behind climate change (known as Working Group I). Last month, the second report was released and discussed climate change impacts, adaptation, and vulnerability already observed and projected in the future (known as Working Group II).

The new report released yesterday (known as Working Group III) discusses actions to limit the magnitude and rate of climate change, termed mitigation. Over 400 experts from over 50 countries were involved in the development of the report, which was accepted by representatives from 195 nations.

Here are 5 key findings from the new lPCC report:

1. Global emissions of heat-trapping gases from human activities have continued to rise. Emissions are dominated by carbon dioxide (mainly from fossil fuel combustion and industrial processes), which account for 78% of total greenhouse gas emissions from 1970 to 2010 (when other gas emissions are weighted to incorporate warming capability relative to CO2). Greenhouse gas emissions have grown more rapidly between 2000 and 2010 than in previous decades despite a recent push to limit emissions; economic and population growth are driving these increases and continue to outgrow emission savings from energy improvements.

2. Action to limit the magnitude and rate of climate change is needed immediately. Climate conditions are changing rapidly as shown in Working Group I, and the impacts to society and ecosystems are unequivocal, consequential, and increasing as shown in Working Group II. Scenarios to limit warming to 2ºC (3.6ºF) relative to preindustrial levels require drastic cuts in greenhouse gas emissions by mid-century through large-scale changes in energy systems and land-use practices. The longer we delay action, the more expensive it will be.

3. It is key to reduce energy demand, deploy low-carbon technologies, and better conserve and manage forestry and agriculture. There is a range of technological and behavioral options for sustainable climate actions; nearly one thousand scenarios were analyzed in the report.

  • Near-term reductions in energy demand through efficiency enhancements in transport, buildings, and industry sectors are cost-effective, provide flexibility for decarbonizing in the energy supply sector, reduce risks in energy supply, and prevent future lock-in to carbon-intensive infrastructures.
  • Behavioral and lifestyle changes—such as lower energy use in households, buying longer-lasting products, changing dietary habits, and reducing food waste—can considerably lower greenhouse gas emissions alongside technological and structural changes. Further development and implementation of low-carbon energy and/or carbon removal technologies is important.
  • Renewable energy technologies—such as wind, hydro, and solar power—have finally achieved a level of maturity to enable large-scale deployment. However, steep challenges exist, including varying costs, regional circumstances, and the existing background energy system.
  • The best climate actions for forestry include afforestation, sustainable forest management, and reducing deforestation. For agriculture, best practices include cropland and grazing land management, and restoration of organic soil. Sustainable agriculture practices can also promote resilience to climate change impacts.

4. Effective actions will only be achieved by international cooperation. Climate change is a global problem because most heat-trapping gases accumulate over time and mix globally. Therefore, emissions by an individual, community, company, or country, affect the globe. The number of institutions for international cooperation is increasing, and sharing knowledge and technologies with other nations speeds up finding solutions. The issue is complicated by the fact that different countries’ past and future contributions to atmospheric greenhouse gas levels are different, as is their capacities to implement actions to limit climate change and build resilience.

5. Co-benefits strengthen the basis for undertaking climate action. Measures to limit energy demand (efficiency, conservation, and behavioral changes) and renewable alternatives can reduce the risk of energy supply, improve public health and the environment by limiting pollution, induce local and sectoral employment gains, support good business practices, improve security of energy supply at the national level, and eradicate poverty. Adverse side effects, such as reduced revenue from coal and oil exporters, can be to a certain extent avoided by the development of carbon capture and storage technologies.

The IPCC will conclude the AR5 in October 2014 with a final report that summarizes the three-part series, recapping the major findings of the physical science of climate change, its effects on society and ecosystems, and actions to avert catastrophic climate change.

There are many ways YOU can help promote climate actions, such as supporting the U.S. to continue its emission-reducing efforts like the EPA’s power plant standards.

Posted in Greenhouse Gas Emissions, International, News, Policy, Science| 1 Response, comments now closed

6 key insights from the latest IPCC climate report

(This post originally appeared on EDF Voices)

Since 1990, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) has released a series of reports that assess the latest data and research on climate change.

The reports are issued approximately every five years. In September 2013, the IPCC issued its newest round of reports by sharing the latest science, concluding with more confidence than ever that humans are responsible and that weather will likely get even more extreme, along with many other key findings.

The newest report, released today, looks at impacts, adaptation and vulnerability. Next month comes the thirdreport in the 3-part series that makes up the IPCC’s 5thAssessment Report (IPCC AR5); it focuses on mitigation—that is, actions to limit the magnitude and rate of climate change.

Over 600 scientists and experts from at least 70 countries were involved in writing this latest installment of the IPCC AR5, which is referred to as Working Group II. Representatives from 195 nations had to approve of the Summary for Policymakers document line-by-line.

The report’s content focuses on three topics:

  • Impacts: effects of climate change on people, society, and ecosystems
  • Adaptation: actions to limit our risks to climate change
  • Vulnerability: the susceptibility of the human and natural worlds to climate change

Here are six key findings from the new IPCC report:

1.       Climate change is now everywhere. Impacts have been found on every continent and across all oceans. Both human and natural systems are experiencing the far-reaching and ever-growing effects: water resources are shrinking; terrestrial, freshwater, and marine species have changed their ways of life; major crop yields have decreased; and heat-related deaths have risen.

2.       Humans and ecosystems are both vulnerable. Climate events such as heat waves, droughts, floods, and wildfires alter ecosystems; disrupt food production and water supply; damage infrastructure and settlements; cause sickness and mortality; and adversely affect mental health and human livelihood. However, people who are socially, economically, culturally, politically, institutionally, or otherwise marginalized are especially vulnerable.

3.       Food security, water resources, human health, ecosystems, and the economy are all at stake. While the degree of risks varies based on climatic and non-climatic factors, scientists are confident that human and natural systems are threatened with continued warming. ‘Runaway’ warming (a global temperature increase of 4˚C (7.2˚F) above preindustrial levels—we are currently at 0.86˚C (1.5˚F)) could make normal activities like growing food or working outdoors impossible in many regions.

4.       Many global risks of climate change are concentrated in urban areas. Heat stress, extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, and water scarcity pose risks in urban areas for people, assets, economies, and ecosystems.

5.       Building resilience is critical to limiting risks… Even the most rigorous mitigation tactics still won’t eliminate some additional warming. The upshot: there are countless opportunities for local, state, and national governments to plan and implement adaptation efforts, and also opportunities for public and private engagements. The down side: several barriers to adaptation still exist (such as legal and financial constraints), and if heat-trapping gas emissions remain unabated and the Earth warms by 4˚C (7.2˚F), the impacts may grow larger than our capacity to adapt.

6.       …but cutting heat-trapping gas emissions is essential. Delaying mitigation actions will likely reduce options for climate-resilient pathways, and make them much less affordable. Fortunately, we can solve two problems at once; examples of actions that build resilience and cut gas emissions include: improved energy efficiency and cleaner energy sources; reduced energy and water consumption in urban areas through greening cities and recycling water; sustainable agriculture and forestry; and protection of ecosystems for carbon storage and other ecosystem services.

Posted in Greenhouse Gas Emissions, News, Science| 2 Responses, comments now closed
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    Megan CeronskyMegan Ceronsky
    Attorney

    Nat KeohaneNat Keohane
    Vice President for International Climate

    Ilissa Ocko
    High Meadows Fellow, Office of Chief Scientist

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    Graham McCahan
    Attorney

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    Climate & Air Policy Specialist

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