Climate crisis blamed for $67bn of Hurricane Harvey damage in 2017, according to a study. The new figure is far higher than previous estimates of the direct impact of global heating, leading to a radical reassessment of the costs of damage from extreme weather.
Harvey caused at least $90bn of damage to property and livelihoods and killing scores of people as it ripped through the Caribbean and the US states of Texas and Louisiana.
About $20bn of the destruction attributed only to the direct impacts of global heating as per conventional economic estimates. Climate breakdown is known to be making hurricanes more robust and may make them occur frequently, but it is complex to separate the effects of global heating from the natural weather conditions that also cause hurricanes.
In a study published in the journal Climatic Change, researchers used the emerging science of climate change attribution for calculating the odds of occurrence of such a hurricane naturally or under increased levels of carbon dioxide and applied the results to the damage caused.
In a separate study published in the same journal last month, similar methods were used and found that droughts in New Zealand between 2007 and 2017 cost the economy about NZ$4.8bn, out of which $800m was directly linked to climate change. Over the same period, out of the insured losses of about NZ$470m caused by floods, NZ$140m was linked to the climate.
The new tools are a more accurate way of estimating the economic damage caused by climate breakdown, the researchers say.
“We’re pretty sure the climate change-related damages associated with extreme events have been underestimated in most assessments of the social cost of carbon,” said David Frame, a professor of climate change at the Victoria University of Wellington and the lead author of the studies. “We think this line of research, as it matures, should provide a really valuable input.”
Friederike Otto, the director, Environmental Change Institute at Oxford, who was not involved in the research, said generating global estimates of the actual cost of climate breakdown became possible due to the method, which could have a profound effect on how governments and businesses approach the urgency to reduce greenhouse gas emissions.
“We have known about the costs of climate change theoretically,” said Otto. “It’s all very well in the abstract, but the global mean temperature does not kill anyone – extreme events cost money and lives. Being able to attribute these impacts to climate change means being able to convey what climate change really means.”
She said the compiling an inventory of the damage that could be attributed to climate change around the world would become possible, which governments and businesses could use to bring about change. “Hopefully this will speed up the process of moving to net zero [carbon].”
Estimating the real costs of the climate crisis could also help developing countries seeking recognition of the loss and damage they face as a result of climate breakdown, which they argue should spur rich countries to provide more assistance. Loss and damage are likely to be one of the most vexed issues at next year’s UN Cop26 climate summit.
Globally legal actions would also be affected, said Tessa Khan, a co-director of the Climate Litigation Network. Activists and local governments all over the world are taking fossil fuel companies to court over their emissions of greenhouse gases. They are arguing that they caused damage knowingly while making a profit from rising carbon dioxide levels.
“[The two new studies] are opening to door to stronger evidence to persuade courts that fossil fuel companies should be held accountable for their role,” Khan said. “This will strengthen the legal basis of these lawsuits.”