World leaders call for action on climate change

The world’s climate is changing in ways that harm people and the environment, a new report charges. And, it adds, people across the globe must take much of the blame. Most will need to stop using fossil fuels by 2100 — or at least stop spewing greenhouses gases by then, the report concludes. If not, far bigger, more dangerous changes are in store.

This is not a cheery message. But it’s one that more than 800 climate scientists from around the world say the public needs to hear. It’s also one that many world leaders seem to accept. On November 11, in Beijing, China, presidents Barack Obama and Xi Jinping issued a joint statement. In it, they pledged to set new targets for cutting carbon dioxide levels. Their lead could be important. Together, these two nations now emit more than one-third of all the world’s CO₂ emissions.

Heat-trapping pollutants are released whenever people burn coal, oil, natural gas and other fossil fuels to create electricity, to heat buildings or to propel vehicles. That’s why scientists call these greenhouse gases. And CO₂ makes up most of that pollution.

People have burned more fossil fuels in the last two centuries — and released more CO₂ — than at any other time in history. As a result, increased temperatures have led to melting glaciers and sea ice, to rising sea levels and to more extreme weather events. CO₂ also has begun making ocean water more acidic.

Together, these changes have made life hard for various creatures on land and in the sea.

As part of the Intergovernmental Panel on Climate Change, or IPCC, climate scientists wrote a series of new reports this year. The latest was released on Nov. 2, 2014, in Copenhagen, Denmark. It sums up what the earlier IPCC reports this year had found. And though dismal, the latest report’s assessment is the most thorough scientific analysis of its type. It has reviewed what is causing climate change, how big the effects have been — and, if things don’t change, how much these impacts are likely to intensify over the rest of this century.

The United Nations Environment Programme and the World Meteorological Organization created the IPCC in 1988. They recruited the world’s top climate experts to analyze the best available data on factors affecting climate. Every few years, these scientists have published detailed assessments of the latest and most reliable research. And every assessment — in 1990, 1996, 2001, 2007 and 2014 — has warned that climate change has the potential to make the world increasingly inhospitable for the species that have adapted to living on it.

So how is the latest report different from earlier ones?

It’s “the urgency and bluntness of the language,” says climate scientist Katharine Hayhoe. She works at Texas Tech University in Lubbock. There, she studies impacts of climate change. She also was an expert reviewer of the IPCC’s 2007 report.

Earlier IPCC assessments were unsure how likely it was that big changes would come. Now there’s far less doubt that dire changes are in store, she notes. In other words, she says, in this report, “the science is even more settled.”

Signs that climate change is under way

An average rise in global surface temperatures is a prime symptom of climate change. And today, global temperatures are about 0.8 degree Celsius (1.4 degrees Fahrenheit) higher, on average, than before the Industrial Revolution. That was in the early 1800s, when people first started burning fossil fuels in large quantities.

Fueling much of that temperature rise, the IPCC says, has been an increase in the air’s greenhouse-gas levels.

After the IPCC’s 1996 report, governments around the world agreed that long-term temperatures should rise no more than 2° C (3.6° F) above what was typical before the Industrial Revolution. What is so special about 2° C? The IPCC scientists concluded that if temperatures rise more than that, very dire changes in weather patterns, crop yields and ice melting could transform life as Earth’s dwellers know it.

To stay below that 2° limit, the IPCC scientists had calculated that society would need to keep atmospheric CO₂ from reaching 450 to 500 parts per million in air. (Parts per million, or ppm, is a measure of the concentration of one thing in something else. Here, it refers to the concentration of CO₂ in air.) This past April, CO₂ levels throughout the northern hemisphere reached a new high: 400 ppm. Overall, CO₂ levels in air are now 42 percent higher than before the Industrial Revolution.

One symptom of this warming has been rising sea levels. Along the U.S. East Coast, for instance, sea levels already have climbed 20 to 25 centimeters (8 to 10 inches) above those before the Industrial Revolution. What’s happening? As ocean water heats up, it expands. Glaciers also have been melting into the ocean, swelling its volume.

This causes problems for people and animals alike. One example: Sea level rise has been making ocean storms more dangerous for people and other coastal dwellers.

In the past, the IPCC reports tended to explain why climate change could be expected. Its scientists couldn’t firmly predict how big the change might be, however, or how soon it might be felt. That has now changed. Scientists who wrote the new report are worried enough that they now recommend immediate action, says Hayhoe of Texas Tech.

By 2050, 80 percent of the world’s electricity must be produced without releasing greenhouse gases into the air, the IPCC now warns. By 2100, it adds, nearly all of the world’s electricity should be produced this way.

Kelly Levin analyzes climate science and government actions for the World Resources Institute in Washington, D.C. This international research group investigates ways that nations can sustain their natural resources. It’s still possible to keep CO₂ levels from rising above 450 to 500 ppm, Levin says. But to do that, nations will need to act now to conserve energy. People also need to switch to renewable energy sources that don’t spew as much CO₂ into the atmosphere. Such sources include solar, wind and hydro power.

“The window hasn’t closed completely, but we need aggressive action,” she says.

U.S. and China pledge aggressive action

The U.S. and Chinese presidents have now said they plan to take aggressive action.

The new U.S. goal that President Obama announced would double the drop in CO₂ emissions already underway. Until now, efforts to cut greenhouse gases had brought about an average drop of 1.2 percent per year (over the period 2005 to 2020). That reduction would now increase to between 2.3 to 2.8 percent annually, the president said. Achieving such a goal would require a rapid move away from use of coal, oil and natural gas. Heavier use of solar, wind and other renewable energy sources could help make such a transition possible.

The president said he thought he could spur this change without relying on new laws. If his plan is going to work, that might be essential. The reason: Many U.S. senators and representatives don’t agree with the president. They challenge whether it’s time for such aggressive action. They don’t even agree on what action might make the most sense.

President Xi’s pledge marks the first time his nation has agreed to cap its CO₂ emissions. The Chinese leader pledged to stop the rapid growth in his country’s CO₂ emissions by 2030. Xi, too, announced plans to boost use of non-fossil fuels. China’s goal, he said, would be to have these alternative energy sources providing 20 percent of his nation’s power by 2030. To do that, China would have to install lots more electricity plants powered by something other than coal. How much more alternative energy would be needed? An amount equal to the power produced by all of the coal plants in China today. That would be an amount equal to almost all of the power now produced — from all sources — in the United States today.  

What you can do

Aaron Huertos says it’s particularly important that students pay attention to the IPCC’s report. He works for the Union of Concerned Scientists in Washington, D.C., helping scientists communicate their research to the public.

Why should teens care? “Climate change is potentially the issue that will define what life will be like when they are adults,” he says. Decisions to burn fossil fuels were made by previous generations. At the time, a lot of people didn’t understand they were causing climate change, says Huertos. But there is now no excuse. We can see the effects of our actions, he says.

There is some good news on the climate front, Huertos notes. People are, for instance, beginning to understand that society must reduce its greenhouse-gas emissions.

Students have a role to play in that effort, he says. Asking school officials to put solar panels on school roofs, to install energy-efficient lighting and to offer charging stations for teachers’ electric cars is a good start.

“Schools are probably the biggest energy user in your lives,” he points out.

Power words

carbon dioxide  A gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten. This colorless, odorless gas also is released when organic matter (including fossil fuels like oil or gas) is burned. Carbon dioxide acts as a greenhouse gas, trapping heat in Earth’s atmosphere. Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food. Its scientific symbol is CO₂.

climate  The weather conditions prevailing in an area in general or over a long period.

climate change Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.

dire    An adjective that means grave, or hard to survive.

fossil fuels  Any fuel (such as coal, oil or natural gas) that has developed in the Earth over millions of years from the decayed remains of bacteria, plant or animals.

global warming  The gradual increase in the overall temperature of Earth’s atmosphere due to the greenhouse effect. This effect is caused by increased levels of carbon dioxide, chlorofluorocarbons and other gases in the air, many of them released by human activity.

greenhouse gas  A gas that contributes to the greenhouse effect by absorbing heat. Carbon dioxide is one example of a greenhouse gas.

greenhouse effect  The warming of Earth’s atmosphere due to the buildup of heat-trapping gases, such as carbon dioxide and methane. Scientists refer to these pollutants as greenhouse gases. The greenhouse effect also can occur in smaller environments. For instance, when cars are left in the sun, the incoming sunlight turns to heat, becomes trapped inside and quickly can make the indoor temperature a health risk.

Industrial Revolution  A period of time in the early 1800s marked by new manufacturing processes and a switch from wood to coal and other fossil fuels as a main source of energy.

inhospitable   A term for conditions that make life unpleasant or hard to survive.

parts per million (billion or trillion)  Frequently abbreviated as ppm (or ppb or ppt), it is a measure of the number of units of some material that is mixed into another. The units should be the same (or equivalent) for both materials. The term is used to describe extremely small concentrations of one chemical dissolved in another. For example, a solution of 300 parts per billion of sodium in water would mean that there are 300 sodium atoms for every billion water molecules.

renewable energy Energy from a source that is not depleted by use, such as hydropower (water), wind power or solar power.

sustainability  To use resources in a way that they will continue to be available in the future.

United Nations Environment Programme  One of the many specialized agencies of the United Nations, this one is headquartered in Nairobi, Kenya. Created in 1972, its role is to serve “as the voice” within the United Nations for the wise and sustainable use of resources throughout the world. It also works to educate people on these issues and to trigger action as necessary to protect the environment.

World Meteorological Organization  Created in 1950, this is a special agency of the United Nations. More than 190 nations and territories belong to WMO, which serves as the official “voice” on the status of the planet’s atmosphere and how it is behaving. WMO is based in Geneva, Switzerland.