Lil’ NAS Express

The fast-tracked update of the 2009 EPA Endangerment finding from the National Academies for Science, Engineering and Mathematics (NASEM), has now been released.

Unsurprisingly, it has come out strongly in favor of strengthening the conclusions of the 2009 finding. Specifically the conclude that:

• Emissions of greenhouse gases (GHGs) from human activities are increasing the concentration of these gases in the atmosphere. … Multiple lines of evidence show that greenhouse gas emissions from human activities are the primary driver of the observed long-term warming trend. No known natural drivers, such as incoming solar radiation or volcanic emissions, can explain observed changes.   
• Improved observations confirm unequivocally that greenhouse gas emissions are warming Earth’s surface and changing Earth’s climate. Longer records, improved and more robust observational networks, and analytical and methodological advances have strengthened detection of observed changes and their attribution to elevated levels of greenhouse gases. Trends observed include increases in hot extremes and extreme single-day precipitation events, declines in cold extremes, regional shifts in annual precipitation, warming of the Earth’s oceans, a decrease in ocean pH, rising sea levels, and an increase in wildfire severity.
• Human-caused emissions of greenhouse gases and resulting climate change harm the health of people in the United States. Climate change intensifies risks to humans from exposures to extreme heat, ground-level ozone, airborne particulate matter, extreme weather events, and airborne allergens, affecting incidence of cardiovascular, respiratory, and other diseases. Climate change has increased exposure to pollutants from wildfire smoke and dust, which has been linked to adverse health effects. The increasing severity of some extreme events has contributed to injury, illness, and death in affected communities. Health impacts related to climate-sensitive infectious diseases — such as those carried by insects and contaminated water — have increased. … Even as non-climate factors, including adaptation measures, can help people cope with harmful impacts of climate change, they cannot remove the risk of harm. 
• Changes in climate resulting from human-caused emissions of greenhouse gases harm the welfare of people in the United States. Climate-driven changes in temperature and precipitation extremes and variability are leading to negative impacts on agricultural crops and livestock, even as technological and other changes have increased agricultural production. Climate change, including increases in climate variability and wildfires, is changing the composition and function of forest and grassland ecosystems. Climate-related changes in water availability and quality vary across regions in the United States with some regions showing a decline. Climate-related changes in the chemistry and the heat content of the ocean are having negative effects on calcifying organisms and contributing to increases in harmful algal blooms. …
• Continued emissions of greenhouse gases from human activities will lead to more climate changes in the United States, with the severity of expected change increasing with every ton of greenhouse gases emitted. …

It’s worth pausing to understand why this is unsurprising. It’s because the evidence for change, for attribution of that change, for model skill, for impacts, and, yes, for harm, is massively greater than it was in 2009. An additional 15 years of observations both in situ, and from satellites. In 2009, Terra/Aqua/Aura had only been observing for a few years. The GRACE records of ice mass loss, ocean mass gain and groundwater depletion were only a few years long. Now it is over two decades. The Argo floats had only just started to be widespread enough to reduce the error on ocean heat content estimates. The key papers on the attribution of single events only started to appear in 2011. The climate model projections available in 2009 were from the CMIP3 ensemble – a group of models that, impressively, continues to successfully predict the global mean temperatures, but which are significantly less skillful compared to current models (CMIP6, or even better, the models being prepped from CMIP7).

2009 was before Harvey, Ida, Florence, Sandy, Irene – events which, while not ’caused’ by climate change, had impacts in the US (via rainfall amounts, intensity, and storm surge) that were very likely enhanced by it.

Rather than the situation being more uncertain than in 2009, we are far more confident in the basics than we were, and where there continue to be uncertainties and (sometimes vibrant) disagreements, these are generally about second order details, or at the cutting-edge intersections between climate and society.

Admittedly, this report was written at an express pace, dictated by the EPA’s actions and deadline and the DOE’s attempt at an end-run around the need for a proper assessment. The chutzpah of the EPA’s supporters complaining that this was done too quickly when they themselves cancelled the National Climate Assessment, set up an illegal FACA-violating ad hoc committee instead and had them report on a ridiculously short timeline with woefully insufficient expertise, is impressive. But even given the short turnaround time, this is an impressive document – mainly because the NASEM can confidently draw on a very broad range of experts and be sure that they are on top of their field.

It’s important to note that this kind of task, impartially advising the government on scientific matters, is exactly what the NASEM was set up to do in 1863. They self-commissioned this report, instead of being asked to do so by the EPA or any of the other relevant agencies, and that is an act of bravery in itself.

Chapeau.