Dec 19, 2019

Rethinking how we describe "business as usual" on climate change

Illustration: Rebecca Zisser/Axios

A new analysis could take a step toward resolving a fiery debate: how to think about — and describe — likely levels of future emissions and warming in light of current trends and planned policies.

Driving the news: Two scientists, in a lengthy post via the Breakthrough Institute, conclude Earth is on track to warm by roughly 3°C above pre-industrial levels by 2100.

  • "This is a far cry from the 1.5°C and 2°C targets enshrined in the Paris agreements, but is also well short of the 4°C to 5°C warming in many 'business as usual' baseline scenarios that continue to be widely used," write Zeke Hausfather and Justin Ritchie.

Why it matters: 3°C means a world far hotter than today.

  • But it's also far less than would likely be enabled by models using high and even unchecked emissions growth — scenarios that they argue, based on extending the International Energy Agency's 2040 analyses through 2100, are no longer in the cards.
  • Hausfather and Ritchie see the most likely outcome from current policies is 2.9°C-3.4°C, but that falls to 2.7°C-3°C if nations meet their existing pledges under the Paris deal.

The big picture: 3°C would mean a lot of damaging outcomes, and even warming to date is causing major harms. A big UN-led report last year explored the consequences of breaching 1.5°C (which is quite likely).

But, but, but: They argue that some commonly cited future "pathways" used in climate literature that bring much higher warming levels are looking quite unlikely for several reasons, including efforts over the past decade to move away from coal.

One level deeper: "Even a current policies scenario where emissions continued to steadily grow rather than leveling off after 2040 would still end up well-below the commonly used RCP8.5 (SSP5-8.5) scenario, which represents the highest end of the range of no-policy baseline scenarios examined in the literature."

The intrigue: Needless to say there's plenty of variables because gaming out the future of technology, policy and economic trends is really dicey. There's also uncertainty about the sensitivity of the climate to rising emissions concentrations.

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10 energy and climate issues to watch in 2020

Illustration: Sarah Grillo/Axios

From presidential politics to China to oil prices, here’s what I’m watching this year.

The big picture: A few key decisive moments this year will help determine whether concerns over climate change — rising since my last two annual outlook columns — will translate into action that would transform our global energy system.

Go deeperArrowJan 6, 2020

California is on track to miss its 2030 greenhouse gas emissions target

Reproduced from California Energy Policy Simulator; Chart: Axios Visuals

A new analysis finds that California is not on track to meet its 2030 greenhouse gas reduction targets absent new and toughened clean energy policies.

Why it matters: California has many of the nation's most aggressive programs, so the results shows the difficulty of achieving steep state-level cuts in that state and others adopting ambitious climate targets.

Go deeperArrowJan 16, 2020

U.S. greenhouse gas emissions fell by estimated 2.1% in 2019

Power lines in California in 2019. Photo: Jane Tyska/MediaNews Group/The Mercury News via Getty Images

U.S. greenhouse gas emissions fell by 2.1% in 2019 due to a decrease in national coal consumption, according to estimates from the Rhodium Group released Tuesday.

Why it matters: Power generated from coal plants fell by a record 18%, and overall emissions from the power section declined by almost 10% — despite an increase in emissions from natural gas.

Go deeperArrowJan 7, 2020