Will Earth’s Climate Get More Sensitive to CO2? Only Better Satellites Can Say

President Trump, his top officials, and Republican leaders in Congress propose to dial back action on climate change, arguing that the scientific consensus on human induced-climate change is unconvincing. That makes resolving scientific uncertainties all the more important. A mathematical analysis published today in the journal Nature Climate Change could explain one of the hottest disputes in climate science: just how sensitive Earth’s climate is to rising levels of CO2.

The metric targeted by University of Washington climatologist Kyle Armour in today’s report—equilibrium climate sensitivity—is the warming at Earth’s surface caused by a doubling of atmospheric CO2. A doubling to 560 parts per million since the Industrial Revolution could occur by mid-century if global economies adopt the Trump Administration’s animosity towards climate action and fossil fuel consumption continues unabated.

Armour’s analysis affirms the range of possible climate sensitivity provided by climate models and the IPCC, which some recent studies argue is too high. His analysis also highlights a need for better satellite equipment to narrow the range—including missions that the Trump Administration placed on the chopping block last month.

Most of the extra heat that Earth has absorbed since the industrial revolution is soaked up by the oceans—more than 90 percent according to the Intergovernmental Panel on Climate Change (IPCC). Measurement of that heat has improved greatly in recent decades thanks largely to the growing array of Argo buoys. There are now 3,947 Argos freely floating around the globe.

A chart showing an increasingly broad orange line rising to the right and fuzzy blue horizontal line. The y-axis is temperature. The x-axis is years beginning at 1900 and ending at 2300.

Narrowing uncertainty as to how much warming CO2 will produce, as seen in the high and low emissions scenarios, will require better Earth observation satellites. Source: IPCC 2014

Climatologists are using their data to make increasingly confident estimates of Earth’s present warming, and then comparing that to atmospheric CO2 concentrations to calculate the sensitivity of the climate. One highly-cited 2013 paper in Nature Geoscience pegs climate sensitivity at 1.9-2.0º C.

That is towards the low end of the 1.5 – 4.5º C range for climate sensitivity endorsed by the IPCC in 2014, and below the 2.2-4.7º C range predicted by leading climate models. This has led some researchers to conclude that climate models simulate a warmer future than is warranted.

Armour’s paper argues otherwise. He asserts that climate models are misunderstood, rather than oversensitive. The answer to the apparent discrepancy between observations and climate models, he says, is that climate sensitivity is a moving target.

It has been noted for several decades that climate models tend to predict that Earth will become more sensitive to CO2 as, for example, polar ice melts, exposing open ocean and land that absorb rather than reflect sunlight. Armour’s work tracks 21 leading models and quantifies the impact.

On average the models simulate a world 150 years hence that is 26 percent more sensitive to CO2 than under present conditions. Armour says this is most likely due to feedback mechanisms that have yet to take off fully, such as the increased absorption of sunlight at the poles as reflective ice sheets and sea ice melt away.

When Armour factored rising sensitivity into that 2013 observation-based Nature Geoscience report and recalculated climate sensitivity, he got a best estimate of 2.9º C—a value well within the IPCC’s consensus range and the range predicted by models. “It reconciles the models with the observations. There’s no evidence that the models are too sensitive,” he says.

Nicholas Lewis, an independent U.K.-based climate scientist and one of the 2013 report’s coauthors, says Armour may be overstating the rise in climate sensitivity. By Lewis’ calculations the increase in climate sensitivity over time is more likely closer to 12 percent, rather than 26 percent.

And he argues that even that smaller bump could turn out to be a figment of the models. “There [is] no observational evidence that climate sensitivity increases with time in the real climate system,” writes Lewis in an email to Spectrum.

For Armour the biggest caveat in his research is the “huge range” of sensitivity shift predicted by the 21 models. While sensitivity never decreased during a model run, it remained flat with a few models and doubled with others.

Armour believes that models reach different outcomes largely by making “different bets” as to how warming will affect cloud cover in different regions. The problem is that today’s best observations can not distinguish which models are simulating cloud feedback ‘correctly’. “We must find ways to place observational constraints on this,” says Armour.

Ocean readings have the required accuracy, but lack the resolution. Satellites provide the opposite—a global high-resolution view without the certainty to pick out the signal of warming-induced change amidst the system’s natural variability.

It is precisely the problem targeted by NASA’s Climate Absolute Radiance and Refractivity Observatory (CLARREO), one of the four missions that the Trump Administration is asking Congress to cancel. CLARREO Pathfinder, the mission’s first phase, would pack a finely calibrated spectrometer designed to cross-calibrate optical sensors on the entire fleet of U.S. and international Earth-observing satellites. Ultimately the mission promises to improve the longterm accuracy of space-based data fivefold to tenfold.

Backers of a complementary U.K.-based mission in development called TRUTHS estimate that their equipment could slash the time required to understand cloud response. Achieving a level of confidence that would require 25-40 years of data from current satellite technology, they say, could be achieved in 12 years with TRUTHS.

Armour says it makes no sense to scrap missions such as CLARREO as a response to uncertainty in climate science: “These are critical programs. They are literally our eyes in the sky.”

It is a point where he and Lewis tend to agree. Lewis says that “CLARREO’s contribution of more accurate and comprehensive data is likely to speed up the reduction in uncertainty,” in estimates of climate sensitivity. That, he says, is a good investment: “I think it better to focus a higher proportion of funding on improving observational data and building up accurate long term records… So in principle I am all for projects like CLARREO and TRUTHS.”

This post was created for Energywise, IEEE Spectrum’s blog about the future of energy, climate, and the smart grid

Trump Dumps Climate Science and Innovation in 2018 Budget Blueprint

NASA’s telescope on DSCOVR snapped a solar eclipse over South America in February

Al Gore didn’t really claim to invent the Internet in 1999, but he did champion a NASA mission that installed a deep space webcam pointed at Earth in 2015. And yesterday President Trump put a bullseye on that mission. Or, rather, on part of it. Trump’s 2018 budget blueprint asks Congress to defund the Earth-facing instruments on the Deep Space Climate Observatory (DSCOVR). Its sensors tracking magnetic storms emanating from the Sun would keep doing their jobs.

Selectively deep-sixing well-functioning instruments on a satellite 1.5 million kilometers from Earth is one of the stranger entries in President Trump’s first pass at a budget request. But it fits a pattern: Throughout the document programs aimed at comprehending or addressing climate change take deep cuts, even where there is no obvious fiscal justification.

“The budget targets almost anything that is related to climate,” observes David M. Hart, who directs the Center for Science and Technology Policy at George Mason University, near Washington, D.C.

Asked about climate change cuts at a press briefing yesterday, Trump Administration budget director Mick Mulvaney stated categorically: “We’re not spending money on that anymore. We consider that to be a waste of your money.” Whether the proposals come to pass, say Hart and other experts, will depend on Congress, and on how much political capital Trump and his administration gain or lose fighting on other issues such as immigration and health care in the months ahead.

Trump’s budget officials swung hardest at the Environmental Protection Agency, verifying earlier leaks that he would ask for a 31 percent slash in funding from its anticipated budget for fiscal 2017 (which ends 1 October). Many programs would lose ground under the proposed $2.6 billion reduction. Those targeted for elimination include the Clean Power Plan, which regulates CO2 emissions from power plants, EPA’s climate change research and partnership programs, and the Energy Star product labelling program—“the most successful voluntary energy efficiency movement in history,” according to its website.

Cuts proposed for the Department of Energy, meanwhile, are deeper than expected and disproportionately hit programs designed to carry energy innovations across the so-called valley of death between basic research and commercialization. Trump’s blueprint would nearly eliminate the department’s applied science offices with a $2 billion reduction, andit zeroes out its tech incubator, Advanced Projects Research Agency-Energy (ARPA-E). ARPA-E had $291 million for fiscal 2016.

The Washington-based Information Technology and Innovation Foundation (ITIF) warned in a statement yesterday that these and other proposed cuts to Federal research and development would, if enacted, “signal the end of the American century as a global innovation leader.”

George Mason University’s Hart, who is also a senior fellow with the foundation, sees an ideological take on the innovation process driving Trump’s cuts. Hart has documented close alignment between the president’s proposals and a budget plan issued by the Heritage Foundation. Heritage, a conservative Washington think tank, argues for a sharp division between government-funded lab research and proprietary corporate-funded product development.

“A more realistic view is that you have a continuum of projects. There’s a broad middle where the benefits are shared and thus the investment should be shared,” says Hart. Bridging that middle ground is critical in today’s power sector, he argues, because deregulation has dried up the cash that once fuelled its cooperative R&D body. “The Electric Power Research Institute still exists, but it’s a shadow of its former self,” says Hart.

Venture capital attracted by ARPA-E-backed energy technologies, meanwhile, shows that DOE’s efforts appear to be paying off.

NASA looks like a budget survivor at first glance—Trump’s blueprint would shave just 1 percent off the agency’s $19 billion 2016 top line and only 5 percent off of its $1.9 billion Earth sciences budget. “That is much less than the Earth science community feared,” says Marcia Smith, president of Arlington, Va.-based consultancy Space and Technology Policy Group and editor of SpacePolicyOnline.com.

Nevertheless, some of the Earth science cuts are potentially pernicious, and all target efforts to understand climate. In addition to 2018 spending cuts, three planned NASA Earth science missions would be scrubbed in addition to the blinding of DSCOVR’s Earth-facing sensors.

In three of the four cases, Trump would forego real benefits to gain minimal budgetary relief. For example, Smith figures NASA might save about $1 million by downgrading DSCOVR. Yet it measures Earth’s albedo, which is a “critical parameter for climate” according to Harvard University atmospheric chemist Steven Wofsy. Its measurements incorporate the scattering of sunlight by clouds and aerosols, which is “a tricky thing to calculate” says Wofsy.

Smith adds that, in her personal opinion, Gore was right about DSCOVR’s unique, full-disc image of the Earth (and the Moon orbiting it): “It is useful to remind people just how fragile the Earth is.” Given the “tiny amount of money” at stake, Smith says that cut “has to count as a political issue, not a money issue.”

Another targeted mission, a follow-on to the Orbiting Carbon Observatory (OCO) that launched in 2014, awaits a 2018 launch. It was assembled from earlier missions’ spare parts and can be cheaply launched since it is destined for the International Space Station.


NASA illustration of its satellite-calibrating CLARREO Pathfinder mission

Whereas the existing OCO-2 scans CO2 emissions across the globe every 16 days, OCO-3 is promises high-precision measurement of regional carbon sources and sinks. One obvious application, he says, is fact-checking greenhouse gas reports. “It could really be powerful … to assess the emissions in China or in India where you can’t trust the numbers,” says Wofsy.

Then there is the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission, whose first iteration is, like OCO-3, to be bolted on to the ISS. CLARREO Pathfinder packs a finely calibrated spectrometer designed to cross-calibrate optical sensors on the entire fleet of U.S. and international Earth observing satellites, thus improving their accuracy 5-10 fold. “It would make sure that what they’re saying about climate is correct,” says University of Colorado senior scientist Michael King, who chairs the U.S. National Research Council’s Committee on Earth Science and Applications from Space.

King says better satellite data should, in turn, boost confidence in climate models, whose findings have been questioned by President Trump and top Administration officials, including EPA Administrator Scott Pruitt and Secretary of State Rex Tillerson. “There are uncertainties in climate models. Improving their accuracy should be in everybody’s best interest,” says King.

Wofsy also worries about unspecified reductions in Earth science research grants, which he calls the “seed corn” for future satellites.

Whether any of these attacks on climate science and action come to pass is ultimately up to Congress, and the reaction yesterday was weak even among Trump’s fellow Republicans. Smith notes that Rodney Felinghuysen, who chairs the House Appropriations Committee, responded with the dry reminder that Congress holds “the power of the purse.”

South Carolina Senator Lindsey Graham, meanwhile, called Trump’s budget “dead on arrival” over its proposed deep cuts to the State Department. And Democrats also issued blistering rejections.

Bill Foster, a physicist representing metropolitan Chicago, said in a statement: “It is hard to overstate how much damage this budget will do to our ability to remain at the forefront of innovation and problem solving.”

How much of the blueprint survives Congress is linked to how the Trump Administration’s credibility and popularity evolves in the months ahead, according to Hart and other budget watchers. “It may depend on how much clout the administration really has, [and] whether they’re deemed to be worth listening to.”

This post was created for Energywise, IEEE Spectrum’s blog about the future of energy, climate, and the smart grid

NASA Launches its First Carbon-Tracking Satellite

Photo: Bill Ingalls/NASA

Photo: Bill Ingalls/NASA

It’s been a rough birthing process for NASA’s Orbiting Carbon Observatory (OCO) satellite program, which promises global tracking of carbon dioxide entering and leaving the atmosphere at ground level. Five years ago the first OCO fell into the Antarctic Ocean and sank, trapped inside the nose cone of a Taurus XL launch vehicle that failed to separate during launch. The angst deepened yesterday when NASA’s Jet Propulsion Laboratory (JPL) scrubbed a first attempt to launch a twin of the lost $280-million satellite, OCO-2, after sensors spotted trouble with the launch pad’s water-flood vibration-damping system less than a minute before ignition.

But this morning OCO’s troubles became history. At 2:56 a.m. PDT a Delta II rocket carrying the OCO-2 satellite roared off the pad at Vandenberg Air Force Base in California. According to JPL, the OCO separated from the Delta II’s second stage 56 minutes later and settled into an initial 690-kilometer-high orbit. If all goes well it will maneuver into a final 705-km orbit over the next month, putting it at the head of an international multi-satellite constellation of Earth-observing satellites known as the A-Train. Continue reading