Three stunningly dire climate change reports have emerged in the last month, including the UN “Emissions Gap” report released this week and the U.S. National Climate Assessment released last Friday. Together, they ring an alarm bell of historic proportions, and must serve as an unprecedented wake-up call to the U.S. and global leaders meeting in Poland next week for key UN climate negotiations.

Yet, even as exigent as they are, these studies still underestimate the risks of runaway, catastrophic climate change, which other reports have found. Simply put, the sum of the science finds that achieving near-term and deep emissions reductions has become manifestly urgent for the safety of nations around the world.

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The United Nation’s “Emissions Gap” report out this week finds that the current emissions reduction pledges from all countries within the Paris Agreement, including the U.S., are far too weak to keep temperatures from increasing less than 2 degrees Celsius pre-industrial levels and provide even a modicum of climate protection. The report notes that the “original [global] level of ambition needs to be roughly tripled for the 2°C scenario and increased around fivefold for the 1.5°C scenario.”

The urgency of action is underscored by the study’s related finding that “Global GHG emissions in 2030 need to be approximately 25 percent and 55 percent lower than in 2017 to put the world on a least-cost pathway to limiting global warming to 2oC and 1.5oC, respectively.”

The high costs to the United States of climate change inaction were compellingly detailed in the fourth U.S. National Climate Assessment released in Washington last Friday. The study found that by the end of the century, warming on current trajectories would cost the U.S. economy more than $500 billion a year in crop damage, lost labor, and extreme weather damages alone, almost double the economic blow America suffered during the Great Recession of 2007-2009. Warming could cut up to a tenth of U.S. GDP by the end of the century, the study found, with over $1 trillion in coastal real estate threatened by rising sea levels and storms.

Heatwaves will cause thousands more deaths and worsen asthma and pulmonary disease through increased air pollution. The report notes that huge costs are already occurring in various ways, from extreme weather events made worse due to climate change, but also in everyday life: “High tide flooding is now posing daily risks to businesses, neighborhoods, infrastructure, transportation, and ecosystems” in the Southeastern U.S., for example. Crucially, the study notes that cutting emissions more quickly now can head off the worse of these impacts.

Last month, the Intergovernmental Panel on Climate Change (IPCC) “Special Report on Global Warming of 1.5°Celsius”, clearly presented the three strategies that must be undertaken to prevent catastrophic warming:

peaking global CO2 emissions by 2020 and moving to zero carbon dioxide emissions before 2050 by expanding clean energy and energy efficiency

deeply cutting short-lived super climate pollutants (methane, black carbon soot, and HFCs)

quickly learning how to remove a significant of the carbon dioxide that is already in the atmosphere

Like the Emissions Gap and U.S. National Assessment reports, the IPCC 1.5 study catalogs the huge climate impacts that are already occurring and the vastly more severe impacts that will be occur without urgent action.

Yet, startlingly, even these important studies and ominous warnings are underestimating the existential nature of runaway climate change by failing to consider the self-reinforcing feedbacks that may push the climate system into chaos before we have time to decarbonize the energy system.

This risk of a “hothouse earth” is outlined in another major scientific study published this summer in the Proceedings of the National Academy of Science finding that the period of time to prevent runaway, uncontrollable climate change is closing much faster than previously understood.

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These cascading, self-reinforcing feedbacks include the loss of the Arctic's sea ice, which currently serves as a shield, reflecting heat back into the atmosphere, but is increasingly being melted into water that absorbs heat. The loss of this sea ice would add tremendous additional warming to the Arctic, which is already warming by at least twice the global average rate. This, in turn, would accelerate the collapse of permafrost and release methane, a super climate pollutant more than 30 times more potent in causing warming than carbon dioxide

Even the three recent reports described above all largely ignore such feedbacks, leaving populations and world leaders not appropriately warned about the cluster of similar climate tipping points anticipated to occur between today’s temperatures and an increase to 1.5 degrees Celsius over pre-industrial levels, let alone the many more feedbacks that will occur if warming reaches 2 degrees Celcius or above.

While President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE alternates between denying climate science or blaming other nations for the problem, only new, deeper emissions reduction commitments in the U.S. and corresponding actions by all nations can prevent the most dire impacts from occurring. There is still time to prevent the worst, and this urgency must begin at the UN negotiations next week. But American citizens and those around the world must put our leaders on notice — act rapidly to prevent climate catastrophe, or we must find leaders who will.

Paul Bledsoe is strategic advisor at the Progressive Policy Institute in Washington, and was a White House climate adviser to President Clinton.

Durwood Zaelke heads the Institute for Governance & Sustainable Development in Washington, Paris and Geneva.