Five Frightening Observations From the Latest International Climate Change Report

Adaptation cannot save us from all the negative impacts of pumping greenhouse gases into the atmosphere

Small island nations such as Tuvalu in the South Pacific face a wide range of threats from climate change, including rising seas that will inundate the land. Australia Department of Foreign Affairs and Aid/Flickr/CC BY 2.0

The impacts of climate change can already be seen around the world, and they’re going to get worse, warns a new report from a panel of global climate scientists.

“Nobody on this planet is going to be untouched by the effects of climate change,” Rajendra K. Pachauri, chairman of the Intergovernmental Panel on Climate Change, said today at a news conference in Yokohama, Japan, announcing the release of Climate Change 2014: Impacts, Adaptation and Vulnerability.

More than 300 authors and editors—an international group of experts in climate science and related fields—contributed to the report, the second of three pieces of the IPCC’s Fifth Assessment Report (AR5). AR5,  when completed, will provide an up-to-date analysis of the state of climate change science. The first part, about the physical science basis for climate change, was released in September 2013.

The report details the many ways in which climate change is now affecting the planet, its ecosystems and humans, as well as how it will get worse as the 21st century progresses. Here are five of the most disturbing observations from the report about the impacts of climate change:

Food production will not keep up with the growing population

The addition of carbon dioxide into the atmosphere is sometimes thought to be a positive when it comes to agriculture, because plants need the gas to grow and thrive. But that’s not the only factor that can affect crop yield. Yield will decline, for instance, when daytime temperatures exceed 30ºC (86ºF).

The report warns that “risks for food security become very significant” when local warming exceeds 4ºC, the upper estimate for global average warming by 2100. Even a 1-degree rise in temperature is projected to negatively impact production of major crops such as corn and wheat.

Overall, we will probably be able to continue increasing crop production, but not fast enough to keep up with population growth. In addition, fisheries, already stressed due to overfishing and other factors not related to climate, will be further threatened by climate change. Given this, spikes in food prices—such as the ones that occurred in 2008, leading to increased poverty and unrest in many countries—will become increasingly likely.

Small islands see big threats

Sea level rise, of course, threatens the future of islands, particularly low-lying ones. But that’s not the only worry.

Ocean acidification is destroying the coral reef ecosystems on which many islanders depend for fishing and other livelihoods and that protect island land. Changing patterns in precipitation and tropical cyclones threaten island residents. Every island won’t be threatened by every threat, but “there is no doubt that on the whole the impacts of climate change on small islands will have serious negative effects especially on socio-economic and bio-physical resources,” the researchers write.

Sea level rise will displace hundreds of millions of people

The low-lying zone of the world’s coasts takes up just two percent of land but it’s home to 10 percent of the world’s population, some 600 million people. That includes 13 percent of the urban population.

As sea level rise creeps up on these regions and inundates them—particularly during storms—land will become unusable and people will have to move. This is especially a worry for low-lying islands and areas of south, southeast and east Asia, such as Bangladesh.

Adaptation cannot prevent all negative impacts from climate change

There are two ways of dealing with climate change: mitigation and adaptation. Mitigation would occur through the reduction of greenhouse gas emissions. Adaptation is when we plan for future changes and take steps to avoid them.

It is not possible to completely mitigate the effects of climate change—even if we stopped emitting greenhouse gases today, there’s enough extra carbon dioxide and other gases in the atmosphere to keep the planet warming for millennia. So a scenario where we reduce emissions still means that people will have to adapt to changes to come. 

However, AR5 warns that adaptation can’t prepare us for everything that’s coming. There are some places and some threats for which there are few if any options for adaptation. No matter what we do, the Arctic will still warm, and permafrost will melt, for instance. The oceans will become more acidic and marine biodiversity will be lost. The water supplies that feed cities will be compromised to some degree. And humans will have to deal with the health effects of higher heat. Climate change will not go away, and we will not be able to find a way to avoid every impact.

At 4 degrees Celsius of warming, climate change becomes the dominant human impact on the planet

Humans have a 10,000-year history of changing the planet to suit our needs. We build cities and roads, clear forests and prairies to plant vast tracts of a single species, dam rivers and wipe out entire species. More than 80 percent of the surface of the Earth has been somehow impacted by the human presence.

But once temperatures rise four or more degrees above the average in pre-industrial times, climate change becomes the “dominant driver of impacts on ecosystems,” according to the report. In other words, just pumping greenhouse gases into the atmosphere will have a bigger effect on the world than any other human action. Quite literally, we’ve outdone ourselves with climate change.

Helen Thompson contributed to this report.

Get the latest Science stories in your inbox.