The world could hit a tipping point that causes warming to spiral out of control — a scenario scientists call ‘Hothouse Earth’
Humans have changed the world’s climate systems by emitting carbon dioxide and other greenhouse gases.
According to a new paper, humans could warm the world so much that we’d cause the planet’s natural climate systems to trigger further warming — a scenario called “Hothouse Earth.”
In that world, the average temperature could rise 4 or 5 degrees Celsius more than it already has, leading to extreme heat and up to 200 feet of sea-level rise .
One frequently sees articles claiming a certain amount of global warming or sea level rise is inevitable based on the amount of CO2 already in the atmosphere. Locked-in warming is commonly estimated to be 1.5 degrees C (2.7° F) above preindustrial levels, about a one-half degree above the current temperature. This is the aspirational target of the 2015 Paris Agreement of the United Nations Framework Convention on Climate Change.
Although there may be some rhetorical benefit in this number, it understates the actual amount of committed warming and sea level rise predicted by mainstream climate change theory. The IPCC says, “Stopping emissions today is a scenario that is not plausible.” Therefore, we will inevitably have higher CO2 concentration than the present, greater warming and more sea level rise.
Under the lowest of the IPCC’s four scenarios, RCP2.6, peak temperature rise of 2 degrees C will be reached before 2100, and sea level rise will be less than about a half meter. However, due to lag effects in ocean warming and ice melt, sea level will continue to rise for centuries. Rise can theoretically be reduced by negative carbon emissions or geoengineering.
According to a peer-reviewed study of more than 5.5 million real estate transactions in Florida, South Carolina, North Carolina, Virginia and Georgia, sea level rise flooding has caused a total home value loss of $7.4 billion since 2005. Scientists from the non-profit First Street Foundation found that depreciation has already taken place in these areas from frequent tidal flooding.
“Within the five states analyzed, South Florida, the Charleston area of South Carolina and Norfolk, Virginia are experiencing some of the worst physical effects and market impact due to sea level rise,” says Steven McAlpine, head of data science at First Street Foundation.
The study used historical property sales data from 2005 to 2017. “Our research both confirmed that property lot flooding does impact homes, and additionally found that neighborhood flooding—which takes the proportion of nearby roads that flood into account—also contributes to slower appreciation of property value,” says Jeremy Porter, statistical consultant at First Street Foundation and professor at Columbia University.