Climate Scientists Encounter Limits of Computer Models, Bedeviling Policy

BOULDER, Colo.—For almost five years, an international consortium of scientists was chasing clouds, determined to solve a problem that bedeviled climate-change forecasts for a generation: How do these wisps of water vapor affect global warming?

They reworked 2.1 million lines of supercomputer code used to explore the future of climate change, adding more-intricate equations for clouds and hundreds of other improvements. They tested the equations, debugged them and tested again.

The scientists would find that even the best tools at hand can’t model climates with the sureness the world needs as rising temperatures impact almost every region.

When they ran the updated simulation in 2018, the conclusion jolted them: Earth’s atmosphere was much more sensitive to greenhouse gases than decades of previous models had predicted, and future temperatures could be much higher than feared—perhaps even beyond hope of practical remedy.

“We thought this was really strange,” said Gokhan Danabasoglu, chief scientist for the climate-model project at the Mesa Laboratory in Boulder at the National Center for Atmospheric Research, or NCAR. “If that number was correct, that was really bad news.”

At least 20 older, simpler global-climate models disagreed with the new one at NCAR, an open-source model called the Community Earth System Model 2, or CESM2, funded mainly by the U.S. National Science Foundation and arguably the world’s most influential climate program. Then, one by one, a dozen climate-modeling groups around the world produced similar forecasts. “It was not just us,” Dr. Danabasoglu said.

‘You solve one problem and create another,’ says Andrew Gettelman, right, at the NCAR Mesa Laboratory; left, NCAR’s Gokhan Danabasoglu.

The scientists soon concluded their new calculations had been thrown off kilter by the physics of clouds in a warming world, which may amplify or damp climate change. “The old way is just wrong, we know that,” said Andrew Gettelman, a physicist at NCAR who specializes in clouds and helped develop the CESM2 model. “I think our higher sensitivity is wrong too. It’s probably a consequence of other things we did by making clouds better and more realistic. You solve one problem and create another.”

Since then the CESM2 scientists have been reworking their climate-change algorithms using a deluge of new information about the effects of rising temperatures to better understand the physics at work. They have abandoned their most extreme calculations of climate sensitivity, but their more recent projections of future global warming are still dire—and still in flux.

As world leaders consider how to limit greenhouse gases, they depend heavily on what computer climate models predict. But as algorithms and the computer they run on become more powerful—able to crunch far more data and do better simulations—that very complexity has left climate scientists grappling with mismatches among competing computer models.

While vital to calculating ways to survive a warming world, climate models are hitting a wall. They are running up against the complexity of the physics involved; the limits of scientific computing; uncertainties around the nuances of climate behavior; and the challenge

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How Amazon decides which climate tech start-ups to invest in

Amazon bought the naming rights to rename Key Arena to Climate Change Arena.

Source: NHL Seattle

If Amazon is going to achieve its goal of net-zero carbon emissions by 2040, it’s going to need to rely on new technology. To spur the process along, the company has a $2 billion venture capital fund to gather and grow climate tech start-ups.

Watching where Amazon is investing is one way to track innovation in the space. It can also give investors a sense of what parts of its own business Amazon intends to prioritize in the future.

“A lot of what we invest for is three to five years out,” Matt Peterson, the head of The Climate Pledge Fund at Amazon, told CNBC. “We try to look around corners to see where our needs are going to be and where the needs of other companies are going to be. I mean, with with a 2040 time horizon, you know, you can’t really afford to look one or two years out, you have to think long term.”

The Climate Pledge Fund, which was announced in June 2020, is funded entirely with money from Amazon’s own balance sheet. For Amazon, the priority is more about incubating the technologies it will need to meet its own climate objectives — making money is good, too.

“If happens to be that the companies we invest in do well and they become the next Tesla or they return a multiple of our investment, then that’s great. It shows that it’s a validation of what it is, but it’s not the main focus of the fund relative to the broader strategic goal,” Peterson told CNBC.

It’s also open to investing in companies at many different stages, and has invested from seed-stage up to series B rounds. “We can invest a million dollars in the company or invest over $100 million in the company,” Peterson said.

Amazon is not alone in investing in climate tech. The space has seen a five-fold increase in investment dollars to $32.3 billion in 2021, up from $6.6 billion in 2016, according to a recent report.

On Wednesday, Amazon announced new investments in Resilient Power and CMC Machinery and a second investment in Infinium. Amazon has previously announced investments in CarbonCure, Pachama, Redwood Materials, Rivian, TurnTide Technologies, BETA Technologies, Ion Energy, and ZeroAvia — bringing the total tally of climate tech start-ups Amazon has invested in to 11.

Amazon is still accepting applications for start-ups looking for funding. The company plans to make investments both large and small.

Here are five areas within climate tech that Peterson told CNBC Amazon is looking to invest in and how those areas track with Amazon’s current or future goals.

Food and agriculture investments

Food production requires a ton of land and fuel, food waste and spoilage result in methane emissions, and dairy and meat production releases in CO2 and methane emissions — all of which are problems for

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