Global greenhouse gas emissions will need to drop to zero by the end of the century if governments hope to prevent massive and irreversible changes to the Earth’s climate, a United Nations’ scientific group warned on Sunday.
The report from the Intergovermental Panel on Climate Change is latest and most dire warning yet that human activities, primarily the burning of fossil fuels like coal, oil and natural gas, are changing the Earth’s climate far more quickly than would have occurred naturally.
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To prevent those permanent changes, which the group says would occur when the planet’s temperature climbs 3.6 degrees Fahrenheit (2 degrees Celsius), countries and industries would have to offset any new emissions by pulling the gases from the atmosphere and burying them underground.
The new “Synthesis Report” draws on data from three previous reports released in the past several months as part of the IPCC’s Fifth Assessment. Those reports were compiled by hundreds of scientists from more than 80 countries who relied on over 30,000 scientific papers.
Sunday’s report release comes a month before about 200 nations will gather in Lima, Peru for United Nations’ talks to try to address the threats from climate change that range from rising ocean levels, more frequent occurrence of ferocious storms, debilitating droughts and devastating heatwaves.
Those talks in Lima, however, are largely a precursor for talks late in 2015 in Paris, where governments will try to forge a long-term plan to battle climate change.
“We have little time before the window of opportunity to stay within 2ºC of warming closes. To keep a good chance of staying below 2ºC, and at manageable costs, our emissions should drop by 40 to 70 percent globally between 2010 and 2050, falling to zero or below by 2100,” R.K. Pachauri, chair of the IPCC, said in a release. “We have that opportunity, and the choice is in our hands.”
So far, most countries have struggled to create long-term plans to address the changing climate. The most ambitious plan so far was announced last month by the European Union, which is targeting a 40 percent cut in its carbon dioxide emissions from 1990 levels by 2030.
President Barack Obama has issued a Climate Action Plan to address the U.S. greenhouse gases, including cutting emissions from power plants by some 30 percent from 2005 levels, but that rule has not been finalized. Republicans, who have long opposed strict climate measures, are poised to win control of the Senate in the midterm elections, and are expected to try to put up road blocks to any measures they say could threaten the nation’s economy or drive energy costs higher.
Secretary of State John Kerry called the report “another canary in the coal mine.”
“We can’t prevent a large scale disaster if we don’t heed this kind of hard science,” Kerry said in a statement. “The longer we are stuck in a debate over ideology and politics, the more the costs of inaction grow and grow.”
Sen. Barbara Boxer (D-Calif.) said in a statement the report showed why the U.S. needs to put a price on carbon as a means of cutting pollution.
“The world’s top scientists are telling Members of Congress and policy makers around the globe that we cannot just try to adapt to climate change. Instead we must act now to reduce dangerous carbon pollution or it will it lead to irreversible impacts for human health, food and water supplies, and vital infrastructure,” she said.
Republicans contend that any efforts by the U.S. to address climate change are bound to fail, since developing nations like China and India are the biggest drivers of pollution increases now.
So far, Beijing has said it supports address climate change, and it has embarked on a massive green energy program, but China continues to increase its consumption of fossil fuels.
According to the IPCC, the amount of carbon dioxide, methane and nitrous oxide in the atmosphere has reached the highest levels in at least 800,000 years, and are “extremely likely” to be driving the climate changes measured since the middle of the last century, the report says.
Global average land and ocean temperatures have risen by about 0.85 degrees Celsius between 1880 and 2012, according to the report, which also acknowledged that the rise in global temperatures had moderated since 1998, when a strong El Nino weather system occurred. Since then, the increase has averaged about 0.05 degrees Celsius per year, it said.
Skeptics have claimed the slower temperature increases cast doubt on the findings that greenhouse gases would seriously affect the planet’s climate.
But the IPCC says that since 1971, it has “high confidence” that most of the increase in energy stored in the climate systems is contained in the oceans, which have seen temperatures near the surface rise by 0.11 Celsius. Only about 1 percent of the increase in energy has been stored in the atmosphere between 1971 and 2010, the report said, compared to more than 90 percent in the oceans.
The IPCC said even if emissions are cut sharply, temperature will continue to increase and ocean levels will still rise, which will require that governments take measures to adapt to the changes even as they must try to cut the emissions. Any cuts in the emissions, it said, will help delay climate changes, reducing the costs of action.
“It is technically feasible to transition to a low-carbon economy,” said Youba Sokona, co-Chair of one of the IPCC’s working groups. “But what is lacking are appropriate policies and institutions. The longer we wait to take action, the more it will cost to adapt and mitigate climate change.”
And given the challenges, one U.S. climate expert said that governments are going to have to hope for a best-case scenario.
“We’re going to have to be lucky in either that the climate is going to be less sensitive than we think it is, or it would have to be lucky with new technological developments falling into our laps, or we’re going to have to act very fast to avoid 2-degree warming,” Michael Oppenheimer, director of the Princeton University program in Science, Technology and Environmental Policy (STEP) told a conference call with reporters.
“And frankly, I personally don’t want to lean too much on luck to get this problem solved, since the fate of the Earth depends on it.”