Quantcast
Environmental News for a Healthier Planet and Life

World's Carbon Budget Is Only Half as Big as Thought

Climate
World's Carbon Budget Is Only Half as Big as Thought

Climate scientists have bad news for governments, energy companies, motorists, passengers and citizens everywhere in the world: to contain global warming to the limits agreed by 195 nations in Paris last December, they will have to cut fossil fuel combustion at an even faster rate than anybody had predicted.

The days of producing electricity from fossil fuels may be drawing to an end. Photo credit: Shutterstock

Joeri Rogelj, research scholar at the International Institute for Applied Systems Analysis in Austria and European and Canadian colleagues propose in Nature Climate Change that all previous estimates of the quantities of carbon dioxide that can be released into the atmosphere before the thermometer rises to potentially catastrophic levels are too generous.

Instead of a range of permissible emissions estimates that ranged up to 2,390 billion tons from 2015 onwards, the very most humans could release would be 1,240 billion tons.

Available Levels

In effect, that halves the levels of diesel and petrol available for petrol tanks, coal for power stations and natural gas for central heating and cooking available to humankind before the global average temperature—already 1 C higher than it was at the start of the Industrial Revolution—reaches the notional 2 C mark long agreed internationally as being the point of no return for the planet.

In fact, the UN Framework Convention on Climate Change summit in Paris agreed a target “well below” 2 C, in recognition of ominous projections—one of which was that, at such planetary temperatures, sea levels would rise high enough to submerge several small island states.

The Nature Climate Change paper is a restatement of a problem that has been clear for decades. Carbon dioxide proportions in the atmosphere are linked to planetary surface temperatures and, as they rise, so does average temperature. For most of human history, these proportions oscillated around 280 parts per million.

The global exploitation, on a massive scale, of fossil fuels drove the expansion of agriculture, the growth of economies, a sevenfold growth in human population, a sea level rise of 14 cms and a temperature rise of, so far, 1 C.

To stop temperatures increasing another 3 C or more and sea levels rising by more than a meter, humans have to reduce fossil fuel emissions. By how much these must be reduced is difficult to calculate.

The global carbon budget is really the balance between what animals emit—in this context, the word animals includes humans with cars and aeroplanes and factories—and what plants and algae can absorb. So the calculations are bedevilled by uncertainties about forests, grasslands and oceans.

To make things simpler, climate scientists translate the target into the billions of tons of carbon dioxide that, ideally, may be released into the atmosphere from 2015 onwards. Even these, however, are estimates.

There is general agreement that a limit of 590 billion tons would safely keep the world from overheating in ways that would impose ever greater strains on human society. The argument is about the upper limit of such estimates.

Dr. Rogelj said:

“In order to have a reasonable chance of keeping global warming below 2 C, we can only emit a certain amount of carbon dioxide, ever. That’s our carbon budget.

“This has been understood for about a decade and the physics behind this concept are well understood, but many different factors can lead to carbon budgets that are either slightly smaller or slightly larger. We wanted to understand these differences and to provide clarity on the issue for policy-makers and the public.

“This study shows that, in some cases, we have been overestimating the budget by 50 to more than 200 percent. At the high end, this is a difference of more than 1,000 billion tons of carbon dioxide.”

The same study takes a closer look at why estimates of the “safe” level of emissions have varied so widely.

One complicating factor has been, of course, uncertainty about what humans might do and another has been about the other more transient greenhouse gases, such as methane and the oxides of nitrogen.

Although short-lived and released in smaller quantities, some of these are potentially far more potent than carbon dioxide as an influence on planetary temperatures.

Complex Calculations

But Dr. Rogelj and his colleagues found that a significant cause of variation was simply a consequence of the different assumptions and methodologies inherent in such complex calculations.

So the researchers have re-examined both the options and the approaches and have worked out a global figure that, they suggest, could be relevant to “real-world policy.”

It takes into account the consequences of all human activity and it embraces detailed outlines of possible low-carbon choices. It also offers, they say, a 66 percent chance of staying within the internationally-agreed limit.

“We now better understand the carbon budget for keeping global warming below 2 C,” Dr. Rogelj said. “This carbon budget is very important to know because it defines how much carbon dioxide we are allowed to release into the atmosphere, ever.

“We have figured out that this budget is at the low end of what studies indicated before and if we don’t start reducing our emissions immediately, we will blow it in a few decades.”

YOU MIGHT ALSO LIKE

Robert F. Kennedy, Jr.: Syria, Another Pipeline War

Al Gore: 3 Questions We Have to Answer About Climate Change

The Biggest Oil Leak You’ve Never Heard Of, Still Leaking After 12 Years

Climate Experts to American Geophysical Union: Reject Exxon Sponsorship

Yves Adams / Instagram

A rare yellow penguin has been photographed for what is believed to be the first time.

Read More Show Less

EcoWatch Daily Newsletter

The Crystal building in London, England is the first building in the world to be awarded an outstanding BREEAM (BRE Environmental Assessment Method) rating and a LEED (Leadership in Energy and Environmental Design) platinum rating. Alphotographic / Getty Images

By Stuart Braun

We spend 90% of our time in the buildings where we live and work, shop and conduct business, in the structures that keep us warm in winter and cool in summer.

But immense energy is required to source and manufacture building materials, to power construction sites, to maintain and renew the built environment. In 2019, building operations and construction activities together accounted for 38% of global energy-related CO2 emissions, the highest level ever recorded.

Read More Show Less

Trending

Houses and wooden debris are shown in flood waters from Hurricane Katrina Sept. 11, 2005 in New Orleans, Louisiana. Jerry Grayson / Helifilms Australia PTY Ltd / Getty Images

By Eric Tate and Christopher Emrich

Disasters stemming from hazards like floods, wildfires, and disease often garner attention because of their extreme conditions and heavy societal impacts. Although the nature of the damage may vary, major disasters are alike in that socially vulnerable populations often experience the worst repercussions. For example, we saw this following Hurricanes Katrina and Harvey, each of which generated widespread physical damage and outsized impacts to low-income and minority survivors.

Read More Show Less
A gray wolf is seen howling outside in winter. Wolfgang Kaehler / Contributor / Getty Images

Wisconsin will end its controversial wolf hunt early after hunters and trappers killed almost 70 percent of the state's quota in the hunt's first 48 hours.

Read More Show Less
Tom Vilsack speaks on December 11, 2020 in Wilmington, Delaware after being nominated to be Agriculture Secretary by U.S. President Joe Biden. Jim Watson / AFP / Getty Images

By Jessica Corbett

Sen. Bernie Sanders on Tuesday was the lone progressive to vote against Tom Vilsack reprising his role as secretary of agriculture, citing concerns that progressive advocacy groups have been raising since even before President Joe Biden officially nominated the former Obama administration appointee.

Read More Show Less