The reality of global warming: We’re all frogs in a pot of slowly boiling water

August 7, 2015
RTX18VKZ-1024x641

Large waves hit the lighthouse and harbour at high tide at Newhaven in Sussex, southern England, February 15, 2014. REUTERS/Toby Melville

In 2009, global leaders agreed to try not to let the world warm more than 2 degrees Celsius above pre-industrial times. This is sometimes seen as a rule of thumb for keeping on the right side of climate change, within “safe” territory.

But that’s not at all how scientists meant it, Professor Camille Parmesan, an expert in biodiversity at the University of Plymouth in the United Kingdom said. Climate risks don’t begin at 2C, she said; it’s more like where they go from high to intolerably high.

The planet has already warmed by about 0.8C (1.7 Fahrenheit) since the late-19th century.

Some of the world’s most iconic places are also the most vulnerable, and they are already feeling the effects.

“We’re already seeing contraction of species in the most sensitive ecosystems, such as those dependent on sea ice or those living on mountain tops,” she said. “We’re also seeing declines in some tropical systems, such as coral reefs, and the valuable services they provide for fish nurseries, tourism and protection from coastal flooding.”

RTR4CL3O

And that’s just the beginning.

“At more than 2C, we wouldn’t just face losing the most sensitive species but some common ones, too,” Parmesan said. “So it wouldn’t just be the polar bear and the Mountain Pika, but other species living in lowland and temperate habitats that aren’t necessarily at risk right now.”

But against this backdrop, the world’s carbon emissions have continued to rise and the task of staying below 2C looms ever larger. Global leaders will meet again in Paris in December to agree on a plan for how to get ourselves on a pathway to achieving 2C in the long term.

But suppose that doesn’t happen.

Suppose we collectively decide the task of keeping to this target is too great, or the price of cutting emissions quickly is too high. What would it mean to resign ourselves to a post-2C world? And if not 2C, then what?

Science is helping to answer these important questions. Climate models tell us that if carbon emissions stay very high, global temperatures could reach 4C above pre-industrial temperatures by the end of the century, perhaps even rising to 5C. And unless emissions cease altogether after that, temperatures will continue to rise long past the end of the century.

And that would mean a world unlike anything we as humans have ever known.

On the path to 4 degrees Celsius

Climate change won’t treat all countries the same. Often the most serious and damaging effects will happen in the countries that are least able to cope.

RTR4CL3Q

A global temperature rise of 4C by the end of the century would see parts of Africa warm by up to 6C, making life near impossible for vulnerable urban populations and people working outdoors.

Drying of river basins and falling crop yields would raise the risk of food and water scarcity in many parts of the world, particularly among poorer rural populations.

Society is vulnerable to extreme weather. The United Nations body whose job it is to assess the science on climate change says the North Atlantic and Western North Pacific will see more strong storms like Typhoon Haiyan that tore through the Philippines in 2013. In Europe, heat waves like the 2003 event, which killed 70,000 people, are already 10 times more likely than a decade ago, and this pattern is set to continue. Scientists also know that warmer air will mean rainfall in heavier bursts, while higher seas will make storms more likely to breach coastal flood defenses.

As humans, we tend to focus on what we experience up here on Earth’s surface. So it’s often overlooked that more than 90 percent of the heat trapped by greenhouse gases goes into the oceans, warming them up from the surface to hundreds of meters below.

The oceans take up some of the extra carbon in the atmosphere, too, making them more acidic. Warming and acidifying oceans spell bad news for marine ecosystems, including valuable fisheries that people the world over depend on for their food and livelihoods.

As seawater warms, it expands. That’s why, throughout Earth’s history, changing temperatures and sea levels have always been closely linked. Since the turn of the 20th century, the global sea level has risen by nearly 20 centimeters, which is already enough to threaten low-lying island nations such as Kiribati, Tuvalu or the Maldives.

Even if the oceans continued this steady march, scientists expect sea levels to be at least another half a meter higher by the end of the century. But the higher temperatures rise, the greater the chances of tipping the balance into a totally altered state, which carries far more serious consequences.

At some point, the vast Greenland ice sheet will collapse. Scientists don’t know exactly when this will happen, but they say it’s likely to be with less than 4C of global warming. The collapse wouldn’t happen quickly, perhaps taking centuries or millennia. But once it starts, we’d be committed to a sea-level rise of several meters. This would inundate some of the world’s biggest cities, including New York and Shanghai.

RTX18VKQ-1024x692

A man photographs large waves hitting the harbor at high tide at Newhaven in Sussex, southern England, February 15, 2014. REUTERS/Toby Melville

At the other end of the globe, scientists are already seeing early signs of collapse in parts of the Antarctic ice sheet. And once that starts, it’s likely to be unstoppable.

In the meantime, almost all the world’s glaciers are losing ice. In the Arctic, temperatures are rising more than twice as fast as the global average, and if we stay on a path to 4C, scientists predict there could be no Arctic sea ice left in summer in as little as 30 or 40 years.

A question of risk

The climate system, in all its infinite complexity, is impossible to predict entirely.

There are some things happening that scientists don’t completely understand yet, such as why ice floating on the sea around Antarctica is currently growing slightly. Scientists think, perhaps counter-intuitively, that it’s down to climate change, too, as the winds encircling the continent push freezing water outward from the coastline, extending the icy platform offshore.

And the climate system could still hold some surprises. As the Arctic warms, the once-frozen ground is thawing and releasing the powerful greenhouse gas methane. Scientists are unsure yet just how much 4C of global warming could speed up this process.

Two, three and four degrees are all points along a global warming continuum. None represents a climate precipice, but it’s clear that as the temperature rises, so do the risks.

What’s left to decide is, how much of a chance are we willing to take? The science is solid enough that whatever we choose, we can’t tell future generations that we didn’t know the risks.

12 comments

We welcome comments that advance the story through relevant opinion, anecdotes, links and data. If you see a comment that you believe is irrelevant or inappropriate, you can flag it to our editors by using the report abuse links. Views expressed in the comments do not represent those of Reuters. For more information on our comment policy, see http://blogs.reuters.com/fulldisclosure/2010/09/27/toward-a-more-thoughtful-conversation-on-stories/

“As the Arctic warms, the once-frozen ground is thawing and releasing the powerful greenhouse gas methane.”

This is still theory as we have not seen the increases in the Alaska North Slope.

All the talk about climate, but nothing about the ever increasing population and the resources required to support them. Sea-level rising (less land mass) and increasing population doesn’t sound sustainable. Fewer people (ie. less electricity consumption, fewer cars, less demand for food) should be part of the discussion, not just less greenhouse gas(es).

The climate changes, and always has. Humans do not like change though. The Earth has not always had a climate conducive to human existence. We are now returning the sequestered carbon (oil, CO2, methane, etc.) back to the atmosphere, which may make the planet a less comfortable place for humans.

Posted by jyy | Report as abusive

“The times they are a’changin”
Things seem to have moved on from the “debate” about the science, with deniers/skeptics rather marginalized to media and politicians sponsored by carbon vested interests. Alternative power generation technology is being deployed, notably in Germany, USA, China. Next is power storage advances, see GE’s latest strategic planning.
But what can be done about nations such as India, Bangladesh, Nigeria, Brazil, … where populations are exploding, largely subsistence agriculture vulnerable to climate change, and 10s of millions in megacities of underemployed poor, and often self-serving corrupt elites in control.
India is investing in new coal mines in Australia and elsewhere to glut the market to keep prices low for coal powered energy generation rather than alternative energy. Oil/gas consumption has various subsidies.
India seemed the worst influence in Copenhagen against a wider global effort, demanding untold billions in “compensation” to do anything, but which would mainly be swallowed by middle class bureaucracy.
These nations seem to be on a path to social collapse, revolutionary rampage, and ethnic/religious/ideological civil war, and 100s of millions of “refugees” from the outcomes of climate change and other factors.

Posted by Neurochuck | Report as abusive

Maybe UN should advocate birth control instead of tax-theft …. oh, my bad … what a no-brainer

Posted by jackdanielsesq | Report as abusive

The difficulty that needs a resolution is the transfer of wealth from the fossil fuel industry to energy conservation and renewable energy either preferably by pricing fossil fuels to reflect C emissions cost on health care,deaths, tax payer subsidies, etc., or regulation.

Posted by Flash1022 | Report as abusive

I don’t know about you, but I intend to go down fighting. So, I’ve decided to join others in the “Pope Francis, We’ve Got Your Back” action on the Mall Thursday, September 24th. That’s the day the Pope will address the Congress. I’m no longer Catholic, more Unitarian then anything, but know the urgency of the problem.

Posted by jackwolf | Report as abusive

jyy
The issue with population as can be observed in the developed world where populations are falling due to the older generation being secure and better life outcomes for offspring etc. Once that is also the experience in the developing world that problem solves itself.
The real problem then is the economic structure that is dependent on constant growth when population thus customer numbers are falling.

Permafrost melt theory, I suggest you find out some facts.
In fact in those fierce blazes they were worsened by the methane and in fact in Alaska, and even Siberia, the ground (melted permafrost ) was actually burning.

The global atmospheric methane concentration is rising, the methane levels in the Arctic have been peaking at high levels

Posted by AbelAdamski | Report as abusive

Cute finishing touch: “we can’t tell future generations that we didn’t know the risks.”
Definitely true if you mean ‘in person’, but for those who are looking for an innocent legacy: ‘The boat has sailed’, ‘the record exists’ or whatever other slur people need, but clearly, we have been warned time and again. The fact that we’re still sitting on the fence staring like said frogs at the expanding seawater has been noted.
But who are we kidding here: It’s not about our future ‘reputation’. When we’re all long gone that has clearly no influence over us. It hardly has influence on us what is happening currently with thousands of people being displaced and migrating as a result, arguably related to a changing climate. And as of yet, we’re not even talking about large areas getting flooded due to the seawater’s thermal expansion, but that could be next.

Posted by benwelgoed | Report as abusive

“In Europe, heat waves like the 2003 event…killed 70,000 people…” The Nature knows better how to solve our problems.

Posted by UauS | Report as abusive

Good day, I have for the first time able to understand the impact of global warming. Thank you for simplified and well written article. We all need to keep a cool head and make joint efforts before its too late.

Posted by Adeelashraf | Report as abusive

Record highs now outnumber record lows 10:1. So that’s….. a kind of warming. It’s happening.

Posted by Solidar | Report as abusive

The cold kills much more people then heat, why nothing on this? A slightly warmer world will probably kill less people.
Every decade viewer people die from extreme weather events, why nothing on this? A growing economy and using fossil fuels to strengthen our defences, build shelters and expand emergency response will probably decrease deaths further.

And why the need to inject the word science or scientist in every paragraph, you are presenting facts, an appeal to autority, ad verecundiam is a logical fallacy.

Posted by VictorJP | Report as abusive

In a sane world sustainability would be a much higher priority. The issue extends beyond climate change. Sustainability means planning our future in a way that we do not set ourselves up to crash and burn at some future date. Long-term planning has not been something politicians excel at or are even good at. Our system is geared at getting politicians reelected and fulfilling the most pressing needs of today.

Things like profit, greed, and quenching our unrelinquishing desire for growth are placed in front of longer term issues and needs. Mapping out a logical and sustainable long-term plan requires delving into some rather hefty philosophical questions like what brings real happiness. (This is not an endorsement of the carbon tax as much as a call for better planning and less waste) More on this important topic in the article below.

http://brucewilds.blogspot.com/2014/04/p lanning-sustainable-future-for-mankind.h tml.

Posted by BruceWilds | Report as abusive