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Climate Challenge ~ An Interview with Climate Scientist Dr. Brenda Ekwurzel

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Karyn Strickler, producer and host of Climate Challenge, the first and only TV show in the nation to focus exclusively on the issue of climate change, did her inaugural interview with Dr. Brenda Ekwurzel, climate scientist from the Union of Concerned Scientists.  They discussed climate change and how to reverse it.

In a recent press release, the Massachusetts Institute of Technology said, “The most comprehensive modeling yet carried out on the likelihood of how much hotter the Earth's climate will get in this century shows that without rapid and massive action, the problem will be about twice as severe as previously estimated six years ago - and could be even worse than that.”

Reversing climate change begins with a fundamental understanding of the issue.  The interview with Dr. Ekwurzel follows:

Karyn Strickler:  Even though most people in the audience have likely seen Al Gore’s documentary, An Inconvenient Truth, let’s start with the basics.  Eleven out of 12 years between 1994 and 2006 were the hottest on record.  July 2005 through June 2006 was the hottest 12 month period in the U.S. since temperature measurement began.  You often hear from skeptics, who have been largely discredited, say that “weather happens.”  How is climate change different from weather?

Dr. Brenda Ekwurzel:  Weather refers to local or regional variations in temperature, precipitation, winds, etc., that occur over short periods, typically, a few days to weeks.  On the other hand, the term climate refers to patterns in average temperature, precipitation, etc., that persist for longer time periods (usually, decades or longer). For example, Phoenix, AZ experiences a desert climate and Montgomery County, MD experiences a temperate climate.  Not all meteorological patterns fit neatly into one or the other of these categories; for example, regional droughts can be of intermediate duration. Climate change refers to shifts in long-term patterns.

Karyn Strickler:  In general terms, how does climate change happen?

Dr. Ekwurzel:  Earth receives energy that travels from the sun in a variety of wavelengths, some of which we see as sunlight and others that are invisible to the naked eye, such as shorter- wavelength ultraviolet radiation and longer-wavelength infrared radiation.

As this energy passes through Earth’s atmosphere, some is reflected back into space by clouds and small particles such as sulfates; some is reflected by Earth’s surface; and some is absorbed into the atmosphere by substances such as soot, stratospheric ozone, and water vapor. The remaining solar energy is absorbed by the earth itself, warming the planet’s surface.

If all of the energy emitted from the warmed Earth’s surface escaped into space, the planet would be too cold to sustain human life. Fortunately, some of this energy does stay in the atmosphere, where it is sent back toward Earth by clouds, released by clouds as they condense to form rain or snow, or absorbed by atmospheric gases composed of three or more atoms, such as water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4).

The net effect is that most of the outgoing radiation is kept within the atmosphere instead of escaping into space. Heat-trapping gases, in balanced proportions, act like a blanket surrounding Earth, keeping temperatures within a range that enables life to thrive on a planet with liquid water.

Unfortunately, these gases—especially carbon dioxide—are accumulating in the atmosphere at increasing concentrations due to human activities such as the burning of fossil fuel in cars and power plants, the clearing of forests for agriculture or development, and agricultural practices. As a result, the insulating blanket is getting too thick and overheating the Earth as less energy (heat) escapes into space.

Karyn Strickler:  In 2007, the statured scientists of the International Panel on Climate Change (IPCC) issued its Fourth Assessment Report and said that it is “very likely” that emissions of heat-trapping gases from human activities have caused “most of the observed increase in globally averaged temperatures since the mid-20th century.” How are humans causing climate change?

Dr. Ekwurzel:  Scientists look over the longer term to tease out exactly how much humans have contributed to recent climate change.  Antarctic ice core records vividly illustrate that atmospheric CO2 levels today are higher than levels recorded over the past 800,000 years.

Atmospheric CO2 levels have risen 36 percent in the last 250 years, with half of that rise occurring only in the last three decades. CO2 (and other gases emitted from industrial and agricultural sources) trap heat in the atmosphere, so it is no surprise that we are now witnessing an increase in global average temperature.

Karyn Strickler:  What ultimately troubles most scientists is the prospect of a dramatic rise in the average global temperature of about 6 to 8 degrees Fahrenheit (3 to 4 degrees Celsius) in the next century, if present trends continue.  “That change is roughly equal in magnitude to the difference between the last ice age and the climate today," according to the book, The Heat is On by Ross Gelbspan.  What are the current estimates for the range of projected increases in average global temperature?

Dr. Ekwurzel:  To account for the uncertainty in heat trapping gas emissions, climate models employ different plausible socioeconomic and energy use storylines to span the range deemed likely.

The Intergovernmental Panel on Climate Change (IPCC), for example, used a set of six IPCC scenarios for its most recent 2007 climate assessment, ranging from low emissions (the “B1” scenario) to high emissions (“A1FI,” in which “FI” represents fossil-fuel-intensive energy use).

The figure depicts the projections for this century for each of these scenarios. The black curves are the averaged projections from 19 climate models.  By the end of this century, the average of the calculated projected temperature rise for the B1 scenario  is  3.2 degrees Fahrenheit (°F),1.8 degrees Celsius (°C), over the 1980–2000 average; in the A1FI scenario, the average of the calculated projected rise in temperatures increases to  7.2°F  (4.0 °C).

The difference between the average of the calculated values of end-of-century temperatures for these two scenarios, therefore, is substantial—nearly 4°F. This underscores the greatest uncertainty about the future are the energy choices we make.  It is worth noting that the world increased global average temperature by a little over a degree Fahrenheit since the dawn of the industrial age and look at how much the climate has already changed.

Karyn Strickler:  Global warming has profound consequences.  You recently wrote a paper entitled, “Latest Climate Science Underscores Urgent Need to Reduce Heat-trapping Emissions.” What are some of the consequences of global warming or climate change?

Dr. Ekwurzel:  Most of us living in the US have already noticed the “creep of the seasons” so that spring arrives earlier and fall starts later.  Evidence abounds in shifting bird migration, budburst dates, river ice breakup and so on.

Winters are getting warmer at a greater magnitude than summers.

The ocean has absorbed most of the excess heat.

The intensity of tropical cyclones (hurricanes) in the North Atlantic has increased over the past 30 years, which correlates with increases in tropical sea surface temperatures.

Increase risk of pests not kept in check over winter as winter temperatures rise.  A dramatic example is the pine bark beetle infestation that has killed many trees making them vulnerable during fire season.  Forest in the Western US, British Columbia and up in Alaska have been devastated by the double plight of pine bark beetle and fire risk.

Storms with heavy precipitation have increased in frequency over most land areas.

Between 1900 and 2005, long-term trends show significantly increased precipitation in eastern parts of North and South America, northern Europe, and northern and central Asia.

Droughts have become longer and more intense, and have affected larger areas since the 1970s, especially in the tropics and subtropics.

Since 1900 the Northern Hemisphere has lost seven percent of the maximum area covered by seasonally frozen ground.

Since 1961, the world’s oceans have been absorbing more than 80 percent of the heat added to the climate, causing ocean water to expand and contributing to rising sea levels. Between 1993 and 2003 ocean expansion was the largest contributor to sea-level rise.  Melting glaciers and losses from the Greenland and Antarctic ice sheets have also contributed to recent sea- level rise.

Karyn Strickler:  Oceans, forests and peat bogs are all types of carbon sinks, that trap and hold CO2, taking it out of the atmosphere.  Please tell us what carbon sinks are and what is happening with them currently.

Dr. Ekwurzel:  For example, as the ocean absorbs carbon dioxide, it becomes more acidic. This combined with increasing ocean temperatures, diminishes the ocean’s ability to absorb CO2 and clean the atmosphere which makes global warming worse.  Hence, a ton of CO2 emitted to the atmosphere today is worse than a ton emitted decades ago because now more of it will remain in the atmosphere trapping heat for a long time.

Karyn Strickler:  Let’s talk in a little more detail about how climate change happens.  Greenhouse gases have remained stable in the atmosphere for thousands of years, but since the beginning of industrialization, greenhouse gases have been on the rise.  What is the evidence that greenhouse gases are on the rise?  What is the most problematic greenhouse gas currently?

Dr. Ekwurzel:  Global warming is primarily a problem of too much carbon dioxide in the atmosphere.  This carbon overload is caused mainly when we burn fossil fuels like coal, oil and gas or cut down and burn forests.

There are many heat-trapping gases (from methane to water vapor), but CO2 puts us at the greatest risk of irreversible changes if it continues to accumulate unabated in the atmosphere. The main reason is that CO2 sticks around in the atmosphere.  Much of today’s CO2 emissions will finally gone in a century, but about 20 percent will still exist in the atmosphere approximately 800 years from now continuously trapping heat.

Karyn Strickler:  Carbon dioxide (CO2) levels have risen higher in the past 100 years, than at any other time in the past 800,000 years.  CO2 lingers in the atmosphere 30 to 100 years or longer.  Doesn’t that mean that even if we dramatically cut CO2 levels tomorrow, that what's up there in the atmosphere, will take a LONG time to come down?  How long will it take?

Dr. Ekwurzel:  Carbon dioxide can be removed from the atmosphere by biological processes (e.g. photosynthesis), through absorption into the oceans, or chemical weathering of rocks.  As we know every year plants take up carbon dioxide and that is a relatively rapid process, yet when they decay that carbon dioxide can be released back.  Of course trees can hold onto their carbon for the life of the tree.  Some of the CO2 is part of a rapid biological exchange.  The oceans can absorb CO2 and become part of the long slow ocean circulation that can take around 800 years for a complete trip around all the ocean basins or CO2 can become incorporated into marine organisms buried in sediments.

An even longer process that takes place over millennia is the removal of CO2 by chemical weathering of rocks.  Unfortunately, a reduction in CO2 emissions still leads to growth in CO2 in the atmosphere as a result of the net effect of these carbon cycle processes.  Only the complete elimination of CO2 emissions would lead to a slow reduction in CO2 in the atmosphere over the next century.

Karyn Strickler:  In the book, Field Notes from a Catastrophe, author Elizabeth Colbert notes that in 1769 when James Watt patented his steam engine, atmospheric CO2 levels were at 280 parts per million (ppm).  Today, CO2 levels stand at about 387 ppm and are increasing about 2.5 ppm annually.  In general terms, what is the relationship between rising CO2 levels and increases in average, global temperatures?

Dr. Ekwurzel:  First we have to compare CO2 in relation to the other natural and human factors that influence climate so-called “climate drivers.”  Natural factors include the energy from the sun; periodic volcanic eruptions of tiny particles, dust, and salt spray—all known as aerosols­­— many that can reflect sunlight; and natural carbon cycle processes such as termite mounds in Africa that emit methane or tiny organisms in the ocean surface that take up carbon dioxide.

Human climate drivers include heat-trapping emissions from burning coal, gas and oil in power plants and cars; cutting down and burning forests; tiny pollution particles known as aerosols; black carbon pollution more commonly referred to as soot; and changes in land use that change how much the Earth’s surface reflects the sun’s energy back into space (referred to as albedo).

Some of these climate drivers result in net warming and others lead to cooling.  When all the natural and human-induced climate drivers are stacked up and compared to one another, the accumulation of human-released heat-trapping gases in the atmosphere is so large that it has very likely swamped other climate drivers over the past half century, leading to observed global warming.

Karyn Strickler:  In his paper, "Target Atmospheric CO2:  Where Should Society Aim," NASA Climate scientist Jim Hansen said recently, "The evidence indicates…that the safe upper limit for atmospheric CO2 is no more than 350ppm."  This is the number around which some groups are beginning to organize.  I interpret Hansen’s statement to mean that we need to aim for a much lower number.  Where do you think we should aim?  Does it make sense that if industrialization caused CO2 to rise, that we should aim for pre-industrial levels?

Dr. Ekwurzel:  If the goal is to avoid some of the worst consequences of climate change then the science evidence points to swift and deep emission reductions.  Since not everyone is used to thinking in terms of atmospheric heat-trapping gas concentrations lets talk temperature goals.

The European Union, and current climate legislation before Congress has as a goal of staying below a 2 degrees Fahrenheit rise above global average temperature today which is 2 degrees Celsius above pre-industrial.

If we take into account the temperature rise above pre-industrial we have already experienced and the heat that is in the pipeline from heat stored in the upper ocean that will continue to heat our atmosphere over the coming decades there is very little wiggle room left so to speak.

According to the IPCC the best estimate for the atmospheric concentration for a 2C rise above pre-industrial would be 441 ppm CO2 eq while 378 ppm concentration (where we are today) would give a 90% chance of staying around 2C rise.  An even lower concentration of 356 ppm CO2 eq would give a 90% chance of staying below 1.6 C rise above pre-industrial levels.

Karyn Strickler:  Often times, cutting greenhouse gases, especially CO2, is put in terms of percentage below 1990 levels because in 1990, the International Panel on Climate Change (IPCC) told the world that in order to stop catastrophic climate change; we must reduce greenhouse gases, mostly carbon dioxide, by 60-80% immediately.  The legislation that recently passed the MD General Assembly, for example, requires reductions in statewide greenhouse gas emissions of 25 percent from 2006 levels by 2020.  Are cuts at the MD level likely to effectively reverse climate change?  If not, what percentage should we cut greenhouse gases and what should be the timeline?

Dr. Ekwurzel:  Maryland is among the leading states that are making commitments to start down a path to help solve the climate challenge.  To set a near-term target for U.S. reductions, we must consider the need to:

1. Limit “lock-in” of carbon-intensive technologies;

2. Guarantee we’re on track to stay within our long-term cumulative budget; and

3. Maintain options if scientific evidence reveals effects are worse than expected.

Taken together, these considerations suggest that near-term reductions should be as swift and deep as possible.

Karyn Strickler:  And of course, CO2 is only part of the story.  The warming currently underway will cause “feedbacks” that further exacerbate the problem and make climate change catastrophic.  Can you tell us a little bit about these “feedbacks?”

Dr. Ekwurzel:  The climate system involves many feedbacks; some are dampening responses (negative feedbacks) in the climate system but overall, the climate feedbacks are positive; i.e., the warming due to heat trapping gases is amplified by the workings of the climate system itself.

Another example of a positive climate feedback is the melting of snow and ice that accompanies the warming triggered by increases in heat-trapping gases in the atmosphere. As the white, highly reflective snow and ice cover diminishes, the Earth absorbs more incoming solar radiation and thus the warming increases. This of course increases the rate of ice melting and the warming accelerates further.

Karyn Strickler:  Katey Walter, an ecologist at the University of Alaska said in New Science, “The permafrost is melting fast all over the Arctic, lakes are forming everywhere and methane is bubbling up out of them.”  Methane is about 25 times more powerful than the main catalyst for global warming, carbon dioxide.  We have entered the perilous period where secondary effects of global warming could take the climate challenge beyond our control.  Please tell us about methane and the role it is playing in climate change.

Dr. Ekwurzel:  The latest IPCC revealed that increased understanding of methane influence on our climate meant methane packs a more powerful heat-trapping punch compared molecule to molecule against CO2 over a 100 year period.  That measure is known as the Global Warming Potential” and the GWP number for methane increased compared to prior assessment reports.

Methane comes from landfills, livestock, large termite mounds, rice paddies, and natural gas.  There are vast stores of methane in the frozen ground of the polar regions and thawing permafrost is one of those feedback mechanisms that can make global warming worse when the carbon is released to the atmosphere.  Methane lingers in the atmosphere for about a decade before it converts to CO2.  

Karyn Strickler:  We’ve all heard that we need to keep our tires inflated, to get better gas mileage; unplug unused electronics and change our light bulbs to use less electricity, but outside of political action - which is critically important - what can individuals do in their daily lives to help to reverse climate change?

Dr. Ekwurzel:  Educate our friends and neighbors and keep track of the options that will keep growing as more consumers demand energy efficient products and demand leadership from business and government.

Karyn Strickler:  There are renowned climate scientists, like Dr. James Lovelock, who believe that we have passed the point of no return on the issue.  As a climate scientist, Dr. Ekwurzel, do you think that climate change still be reversed?  If so, what’s it going to take?

Dr. Ekwurzel:  The oceans have been buffering us for the past decades of climate change and bought us a little bit of time to turn this around before those factors that will really amplify the warming take hold.  Delay is costly both in a climate science sense and in an economic sense.

Karyn Strickler:  The challenges we face provide an opportunity for extraordinarily positive change.  Dr. Ekwurzel, what do you see as the most hopeful change that will come from our efforts to reverse climate change?

Dr. Ekwurzel:  I liken our resistance to rolling out energy solutions that are climate friendly to the resident’s of London during the time of coal-fired stoves that created the thick soot filled air.  They must have thought, whatever the long-term health risks, we need to heat our homes today.  At that time the situation was resolved with improved home heating systems.

Climate friendly energy solutions mean we can have cleaner air to breathe and dramatically less pollution to our environment that currently results from a heavy reliance on fossil fuels.

We don’t have to import most of our energy needs from other countries.  We have energy jobs that can’t be outsourced as we need folks here maintaining those renewable energy sources that harness the wind or sun within our borders.

Renovating our aging infrastructure and buildings to be more energy efficient means even more jobs in our communities.  The best part is if we deploy even current technologies to their fullest potential it would mean lower energy bills per month and less money at the pump for the same distance traveled.

© Karyn Strickler 2009. Karyn is a senior fellow with the Center for New Politics and Policy in Washington, DC.

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Karyn Strickler is a political scientist, grassroots organizer and writer. She is founder and president of Vote Climate U.S. PAC, working to elect candidates to get off fossil fuels and put a price on carbon. Karyn is the former host and (more...)

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