Month in Review ~ April 2024

2023 was a weird weather year, wasn’t it? / 02

Global forest carbon storage, explained / 04

In memoriam: Bill Pisano / 06

Upcoming events / 06

In the news: highlights / 07

Month in Review ● April 2024 woodwellclimate.org

2023 was a weird weather year, wasn’t it?

Climate scientists weigh in on what 2023’s record breaking temperatures say about climate models.

Sarah Ruiz Science Writer/Editor

We can all agree 2023 was a weird year for weather, right?

The United States set a record for the number of billion dollar weather disasters. A major Amazon River tributary reached its lowest water levels in a century during extreme drought. Extreme rain in Libya caused two dams to break, destroying homes and killing over 4,000 people.

And then, of course, there was the heat. 2023 was the hottest year on record. Countries around the world saw heat records fall month after month. The Arctic was hot. The ocean was hot. And debates swirl on about whether we’ve already passed critical warming thresholds.

So how do we put 2023 in context of the greater trend of warming? Here’s what some of Woodwell Climate’s scientists have to say about last year’s record-breaking events.

Did the models predict this?

The dramatic scenes of heat and extreme weather last year prompted many to ask why temperatures had seemingly spiked

way above the trend line. Was this unexpected? Was it out of the range of what scientists had modeled? Woodwell Senior Scientist Dr. Jennifer Francis says not entirely.

“Almost exactly a year ago,” says Francis, “we had just come out of three years of La Niñas and we came close to breaking global temperature records then, even though La Niñas tend to be cooler than neutral or El Niño years. And then along came the strong El Niño of 2023.”

El Niño and La Niña are two extremes of a natural phenomenon that impacts weather patterns across the Pacific, and around the world. In an El Niño year, the prevailing trade winds that normally push warmer waters into the western tropical Pacific— allowing cooler water to well up along the western coast of the Americas—are reversed, resulting in hotter ocean surface temperatures in the eastern equatorial Pacific. When the ocean is hotter than the air above it, that heat is released into the atmosphere, often making El Niño years record-breaking ones for global temperatures.

“Last year’s spike looks a lot like the last big El Niño event in 2015–2016. It’s just that now the whole system is warmer. So to me, it wasn’t at all a surprise that we smashed the global temperature record in 2023,” says Francis.

The spike put global temperatures far above the average of climate model simulations, but that doesn’t mean the models didn’t account for it. Risk Program Associate Director Dr. Zach Zobel, says that averages tend to smooth out natural year-toyear fluctuations, when in fact the upper and lower ranges of model predictions do encompass temperatures like the ones seen in 2023.

“It was well within the margin of error that you would expect for natural variations,” says Zobel.

How does ocean heat impact the climate?

One element of last year’s heat, one that wasn’t necessarily forecasted, was the simultaneous appearance of several ocean heat waves around the globe. The ocean absorbs the vast majority of heat trapped by greenhouse gasses, and that heat can be released under the right conditions. El Niño is one example, but in 2023 it coincided with other not-so-natural marine heat waves across the world.

“In pretty much every single ocean right now there are heat waves happening, which is something quite new,” says Francis.

A couple of dynamics could be driving this. One possibility is that after three years of La Niñas, in which equatorial Pacific

ocean temperatures were generally cooler than the air, the ocean simply absorbed a lot of heat, which was then primed to be released in an El Niño year. Another, Zobel suggests, could be recent shipping laws that required shipping vessels to eliminate sulfate emissions by 2023. Sulfates are a pollutant that may have been helping bounce back solar radiation, hiding the true extent of warming.

“Usually when there’s an El Niño, the eastern tropical Pacific is very warm, but it doesn’t actually drive up ocean temperatures everywhere,” says Zobel. “That was the biggest surprise to me: how warm the northern hemisphere of the Atlantic and Pacific were for most of last year and into 2024.”

Ocean heat waves are typically long-lived phenomena, lasting many months, and so can be a useful tool for meteorologists looking to predict 2024’s extreme weather events.

“The good news is that it provides some kind of long-term predictability about weather patterns in the upcoming year,” says Francis. “The bad news is that they tend to be unusual weather patterns, because those ocean heat waves aren’t usually there.”

Will next year be hotter?

So are we in for another, hotter year after this one? Risk Program Director Dr. Christopher Schwalm says it’s likely.

“Warming predictions for 2024 from leading scientists all forecast a higher level of warming this year than last year,” says Schwalm.

Already, March 2024 was the 10th month in a row to break temperature records. Zobel says it’s typical for the year following an El Niño peak to maintain high temperatures.

“Because the ocean spent a good amount of the year last year warmer than average, that energy is typically dispersed throughout the globe in the following year,” says Zobel. “So even though the tropical Pacific might return to normal, that energy is still in the system.”

However, atmospheric scientists are already seeing signs that El Niño is slowing down and flipping to its counterpart, La Niña, adding another layer of complexity to predictions for 2024.

“The 2024 hurricane season is a large concern,” says Zobel. “La Niña is a lot more conducive to tropical cyclone development. If we combine above average numbers with the amount of energy that storms have to feed on, it’ll be a shock to the system.”

What does this mean for 1.5?

In the discussions around 2023’s temperatures, one number dominates the conversation: 1.5 degrees C. This is the amount of warming countries around the world agreed to try to avoid surpassing, in accordance with the United Nations’ 2015 Paris Climate Agreement. Estimates from Berkeley Earth say that 2023 may have been the first year spent above that threshold.

This assertion may take several years to verify—one year spent physically above 1.5 degrees of warming does not indicate the UN threshold has been permanently passed. What scientists are looking for is a clear average trend line rising above 1.5 degrees C without coming back down, and for that you need several years of data. That, regrettably, creates a lag time between climate impacts and updating climate policy. But for many, the debate around the arbitrary 1.5 degree goal has become a distraction. Schwalm says scientists and policy-makers should be focusing on urgently combating climate change whatever the numbers say.

“We are already living in a post-Paris Agreement reality,” says Schwalm. “The sooner we admit that and reimagine climate policy, the better.”

“Actual real world impacts are going to be there, whether we’re at 1.48 or 1.52,” says Zobel.

And Francis agrees. “There are so many indicators telling us that big changes are underfoot, that we are experiencing major climate change, but reaching 1.5 isn’t going to all of a sudden make those things worse. It’s just one more reminder we’re still on the wrong track and we’d better hurry up and do something.”

Global forest carbon storage, explained

Protecting forests is one of our best climate solutions. Here’s how forests around the world store carbon.

Sarah Ruiz Science Writer/Editor

When it comes to reversing climate change, trees are a big deal. Globally, forests absorb nearly 16 billion metric tonnes of carbon dioxide per year, and currently hold 861 gigatonnes of carbon in their branches, leaves, roots, and soils. This makes them a valuable global carbon sink, and makes preserving and maintaining healthy forests a vital strategy in combating climate change.

But not every forest absorbs and stores carbon in the same way, and the threats facing each are complex. A nuanced understanding of how carbon moves through forest ecosystems helps us build better strategies to protect them. Here’s how the world’s different forests help keep the world cool, and how we can help keep them standing.

Tropical forest carbon

Tropical rainforests are models of forest productivity. Trees use carbon in the process of photosynthesis, integrating it into their trunks, branches, leaves, and roots. When part or all of a tree dies and falls to the ground, it is consumed by microorganisms and carbon is released in the process of decay. In the heat and humidity of the tropics, vegetation grows so rapidly that decaying organic matter is almost immediately re-incorporated into new growth. Nearly all the carbon stored in tropical forests exists within the plants growing aboveground.

Studies estimate that tropical forests alone are responsible for holding back more than 1 degree C of atmospheric warming.

75% of that is due simply to the amount of carbon they store. The other 25% comes from the cooling effects of shading, pumping water into the atmosphere and creating clouds, and disrupting airflow.

In many tropical forest regions, there is a tension between forests and agricultural expansion. In the Amazon rainforest, land grabbing for commodity uses like cattle ranching or soy farming has advanced deforestation. Increasing protected forest areas and strengthening the rights of Indigenous communities to manage their own territories has proven effective at reducing deforestation and its associated emissions in Brazil. “Undesignated lands” have the highest levels of land grabbing and deforestation.

Fire has also become a growing threat to the Amazon in recent years, used as a tool to clear land by people illegally deforesting. When rainforests have been fragmented and degraded, their edges become drier and more susceptible to out-of-control burning, which weakens the forest even further. Enforcing and strengthening existing anti-deforestation laws are crucial to reduce carbon losses.

In Africa’s Congo rainforest, clearing is usually for small subsistence farms which, in aggregate, have a large effect on forest loss and degradation. Mobilizing finance to scale up agricultural intensification efforts and rural enterprise within communities, while implementing protection measures, can help

decrease the rate of forest destruction. Forests and other intact natural landscapes such as wetlands and peatlands could be the focus of climate finance mechanisms that encourage sustainable landscape management initiatives.

Temperate forest carbon

Much of the forest carbon in the temperate zone is stored in the trees as well—particularly in areas where high rainfall supports the growth of dense forests that are resilient against disturbances like drought or disease. The temperate rainforests of the Northwestern United States, Chile, Australia, and New Zealand contain some of the largest and oldest trees in the world.

Two thirds of the total carbon sink in temperate forests can be attributed to the annual increase in “live biomass”, or the yearly growth of living trees within the forest. This makes the protection of mature and old-growth temperate forests paramount, since older forests add more carbon per year than younger ones and have much larger carbon stocks. Timber harvesting represents one of the most significant risks to the carbon stocks in temperate forests, particularly in the United States where 76% of mature and old growth forests go unprotected from logging. Fire and insects are also significant threats to temperate forests, particularly in areas of low rainfall or periodic drought.

Maintaining the temperate forest sink means reducing the area of logging, both by removing the incentive to manage public forests for economic uses and by providing private forest owners with incentives to protect their land. Low-impact harvesting practices and better recycling of wood products can also help bring down carbon losses from temperate forests. In areas threatened by increasingly severe wildfires, reducing fuel loads—especially near settlements—can help protect lives and property.

top: Flooded lowland rainforest in Brazil. / photo by Mitch Korolev

bottom: Forest cleared for timber harvest in Howland Forest, Maine. / photo by Jonathan Kopeliovich

In boreal forests, the real wealth of carbon is below the ground. In colder climates, the processes of decay that result in emissions tend to lag behind the process of photosynthesis which locks away carbon in organic matter. Over millennia, that imbalance has slowly built up a massive carbon pool in boreal soils. Decay is even further slowed in areas of permafrost, where the ground stays frozen nearly year round. It estimated that 80 to 90% of all carbon in boreal forests is stored belowground. The aboveground forest helps to protect belowground carbon from warming, thaw, decay, and erosion.

Wildfire—although a natural element in boreal forests— represents one of the greatest threats to boreal forest carbon. With increased temperatures, rising more than twice as fast in boreal forests compared to lower latitudes, and more frequent and long-lasting droughts, boreal forests are now experiencing more frequent and intense wildfires. The hotter and more often a stand of boreal forest catches fire, the deeper into the soil carbon pool the fire will burn, sending centuries-old carbon up in smoke in an instant. Logging of high-carbon primary forests is also a big issue in the boreal.

The number one protection for boreal forest carbon is reducing fossil fuel emissions. Only reversing climate change will bring boreal fires back to the historical levels these forests evolved with. In the meantime, active fire management in boreal forests offers a cost-effective strategy to reduce emissions—studies found it could cost less than 13 dollars per ton of carbon dioxide emissions avoided. Strategies for fire management included both putting out fires that threaten large emissions, and controlled and cultural burning outside of the fire season to reduce the flammability of the landscape.

In Memoriam

With sadness, we share that Woodwell Climate Board member William (Bill) Pisano passed away on March 26, 2024. During his long career as an engineer, Bill played an integral role in major infrastructure projects in the greater Boston area. He joined the Woodwell Climate Board in 2018. We send our deepest sympathies to his wife and family.

Upcoming

ALASKA Evening at the Museum with the Permafrost Discovery Gateway

A 30 minute science talk and Q&A on how big geospatial data and AI can help communities monitor and plan for permafrost thaw.

COLORADO

Woodwell Climate @ Mountainfilm

Woodwell Climate returns to Mountainfilm as a nonprofit partner, hosting events for festival attendees to engage with climate change.

MASSACHUSETTS

In Flux: Perspective on Arctic change

An exhibition of new works inspired by Arctic research of Woodwell Climate scientists.

A closer view of a boreal forest floor. / photo by Brendan Rogers

Boreal forest carbon

In the news: highlights

The International Cryosphere Climate Initiative’s COP28 video of the week for early April was “What everyone should know about permafrost thaw,” featuring Dr. Sue Natali and moderated by Abby Fennelly.

An article from NBC about how melting polar ice caps are slowing Earth’s rotation quoted Dr. Jen Francis, who reminded readers of the bigger concern around melting land ice—sea level rise.

Pará Online published an article on a recent study co-authored by Dr. Marcia Macedo, which highlights how Indigenous lands and conservation units help protect forests and regulate climate.

An article in Marin Living Magazine highlights the upcoming Sun Valley Forum, and lists Dr. R. Max Holmes as a speaker.

Phys.org published a press release by the University of Oxford highlighting a recent paper led by Dr. Manu Machado: “Emergency policies are not enough to resolve Amazonia’s fire crises.”

The government website for the Republic of Slovenia published a news article about Ambassador Iztok Mirošič’s participation in a panel with Dr. Sue Natali at the Arctic Encounter Symposium.

In a one-pager, The Center for Excellence in Disaster Management & Humanitarian Assistance cited Woodwell Climate’s case study on climate security in North Korea, written in collaboration with the Center for Climate and Security.

Dr. Richard Birdsey was interviewed for an article in Columbia Insight that explains why no one knows exactly how much oldgrowth forest we have left.

Dr. Heather Goldstone was a guest on an episode of WCAI’s The Point, which focused on the benefits of having worldclass science organizations in the area that engage local communities.

An article from The Chronicle about enhancing sustainable forest management practices with blockchain technology mentioned Woodwell Climate’s launch of the Trase platform, which provides data and trade flow information for jurisdictional and supply chain due diligence.

An article about drought published on Medium cited Woodwell Climate’s story by Sarah Ruiz and Christina Shintani about the impacts of drought in Panama on shipping.

AP News quoted Dr. Jen Francis in an article announcing that March was the 10th straight month to be the hottest on record. The article was syndicated to outlets around the world over 650 times.

The April edition of EOS spotlighted a research article about the importance of southern Alaska forests for our climate goals, which Dr. Rich Birdsey contributed to.

Dr. Chris Neill was quoted about his experience feeling the recent New Jersey earthquake at the Center in an article for The Boston Globe

Fly Fisherman published a feature article about Science on the Fly, quoting Allie Cunningham, Dr. R. Max Holmes, and Board Member John Land Le Coq.

Dr. Sue Natali was mentioned in an article by High North News previewing the annual Arctic Encounter conference in Anchorage, AK.

Dr. Kyle Arndt was interviewed about his research on adding seaweed to cow diets and its impact on methane production for an article by Manure Manager.

Isabel Wargowsky spoke with the Integrated Carbon Observation System (ICOS) about how she uses ICOS data and why better monitoring of carbon fluxes in the Arcticboreal region is key to informing more accurate global carbon budgets.

IPAM Amazônia published an article on their website covering collaborative research with Woodwell Climate, which showed that riparian forest protection must be expanded to protect biodiversity.

Reuters quoted Drs. Mike Coe and Manoela Machado in an article about wildfires in Venezuela amid a climate-driven drought. The article was republished in outlets around the world.

A widely-syndicated article from AP News closed with a quote from Dr. Jen Francis, who provided context on a study that found climate change is making heat waves last longer, spike hotter, and hurt more people.

Dr. Peter Frumhoff was quoted in a Nature article about the cancellation of a controversial solar engineering study led by Harvard researchers.

Phys.org published a press release from the University of Utah that quotes Dr. Jon Sanderman about the importance of nature based climate solutions for our climate future. Earth.com also wrote a story based on the press release.

In celebration of Earth Day, we shared examples of our timely and impactful work around the globe on social media. Check it out and share to spread the word!

Mato Grasso, Brazil. / photo by Mitch Korolev