Scientist explains why geo-engineering the atmosphere elevates risk for future generations

French paleoclimatologist Valérie Masson-Delmotte has something important to say to those who believe that geo-engineering could save humanity from the effects of global warming.

Masson-Delmotte, who's in Vancouver for a panel discussion this evening on climate change, told the Georgia Straight by phone that injecting aerosols into the upper reaches of the atmosphere could hypothetically control surface warming.

That's because these particles would reflect sunlight back toward outer space, potentially offsetting the risks of higher concentrations of greenhouse gases.

"But it has side effects," Masson-Delmotte cautioned. "You cannot compensate for ocean acidification. You alter dramatically the global water cycle because when you do that, you change the heat budget of the atmosphere."

That, in turn, could have a profound impact on monsoons, which provide the water upon which more than a billion people in South Asia depend on to maintain crops that keep them alive.

Masson-Delmotte, who coordinated the Intergovernmental Panel on Climate Change's chapter on past climates, highlighted another concern.

Because geo-engineered particles only have a lifetime of a couple of years, she pointed out that they would have to be continually replenished as greenhouse-gas levels continue rising. That's because carbon dioxide remains in the atmosphere for more than 100 years.

"So imagine you keep injecting each year more greenhouse gases and you mask the effect on temperature by aerosols in the high atmosphere for 60 or 70 years, and then you stop," Masson-Delmotte said. "What happens? Instead of having a gradual warming over 70 years, you get the same amount in 15 years. So you expose the next generation to, in fact, a much higher risk of disruption."

Speed of warming exceeds anything seen before

Masson-Delmotte said that climate change is taking place at a faster rate than ever before.

And that raises alarming prospects if greenhouse-gas emissions continue on a business-as-usual path with no mitigation measures.

"From the ice age to a warming period, the pace of warming was something like one degree per 1,000 years on average at the global scale," she said. "We are talking about four degrees in this century. So it's really something that's unusual for homo sapiens both in magnitude and rate of change."

She suggested that if companies or governments decide to try to geo-engineer the climate, that could potentially impose legal liability in case anything goes wrong. For this reason, she doesn't believe any insurance companies will want to underwrite the risk.

"I believe that if one would estimate the cost, it would be extremely difficult to be insured for any case study of large-scale geo-engineering," she said.

Ice cores reveal magnitude of change

Masson-Delmotte is part of an international research team involved in the Northern Greenland Eeemian Ice Drilling, known as NEEM, which published its findings in Nature in 2013.

She explained that the cores provided a wealth of information about the interglacial period before the last ice age some 125,000 years ago.

"The position of the earth was different around the sun and therefore the amount of incoming solarization at high latitudes in summer was strongly enhanced," Masson-Delmotte said.

On a global scale, she said there was no change in the average temperature, but the seasonal distribution of solar radiation was different.

According to Masson-Delmotte, this provided a case study about the cause of changes and the types of feedbacks that were amplified.

"This period was not that much different from present day," she noted. "We think it was less than two degrees warmer than today, but with a large warming in the Arctic and a large ice retreat."

Here's the shocker: "We also know that sea level was higher than today by five to 10 meters. Our best guess at the moment is six meters."

Masson-Delmotte pointed out that this massive rise in sea level cannot be explained by ocean warming or the expansion of all of the small glaciers that existed at the time.

This partial deglaciation leading to sea level rise, she explained, mostly came from Greenland and the Antarctic ice sheets.

"We have an estimate of temperature change locally in Greenland," she added. "We estimate it was up to seven degrees above present-day during several thousand years."

By combining information about the changes in the thickness of the ice, researchers concluded that melting on Greenland added between 1.5 to 4.3 meters of seal-level rise.

"It also implies that the Antarctic ice sheets were also vulnerable and contributed a couple of meters to sea level," Masson-Delmotte stated.

Lessons for the present 

The significant of the NEEM research, according to Masson-Delmotte, is that there were no tools beforehand to test the accuracy of ice-sheet models as climate change continues. 

"We want to test them against real changes, not just the last century, but large changes that are comparable to what we project for the coming century," she said. "The last interglacial period is really nice for that because we are comparing for different reasons the response to the climate system to a perturbation around the Arctic."

It shows the same magnitude of change as what's expected in an increase of two or three times on atmospheric carbon dioxide since preindustrial times.

Next year in Paris, France will host COP21, also known as the 21st Conference of the Parties on Climate Change 2015.

Signatories to the 1997 Kyoto Protocol have indicated a willingness to reach a new agreement, which would take effect in 2020.

Masson-Delmotte said the 2009 conference in Copenhagen was seen by some as a failure because it was characterized as "the planet or nothing".

"This gave a lot of space in the media for [climate-change] denial," she noted. "Being in a situation of not having a solution feeds that denial in a way."

She said that the French foreign-affairs ministry has adopted a different approach for next year's event.

"They will not have one key success indicator," Masson-Delmotte noted, "but a number of steps. Some of them may seem small, but they want to have things that are feasible, verifiable, and for which you can observe success both at the negotiation phase but also in the coming years."

It may strike some as less ambitious, but Masson-Delmotte emphasized that it's also, in a way, more pragmatic.

This evening (November 12), Masson-Delmotte will participate in a panel discussion with two other French and three B.C. climate-change experts at a sold-out event tonight at the Goldcorp Centre for the Arts at SFU Woodward's. The other panelists will be B.C. Green MLA and climate scientist Andrew Weaver, Pacific Institute for Climate Solutions director Tom Pedersen, SFU professor and IPCC member Mark Jaccard, former French environment minister Corinne Lepage, and Daniel Zimmer, who's with the European Institute of Technology.