Latest news with #EdwardBlanchard-Wrigglesworth
Hindustan Times
4 days ago
- Science
- Hindustan Times
Smoke from boreal wildfires could cool the Arctic
There are two things which climate scientists hate about 'positive feedbacks'. One is that they are bad news. A positive feedback, in the science of complex systems, is an amplification; in climate change, this comes about when a consequence of rising temperatures drives a further rise in temperature. Such feedbacks are the sorts of things that drive tipping points. The other problem is that they sound like good news. Negative feedbacks face the opposite problem. In a negative feedback, which need not be harmful, a change in the system produces a response that pushes the system back towards where it was. Think of an air conditioner's temperature setting or a radiator's thermostat. A recent analysis by Edward Blanchard-Wrigglesworth of the University of Washington and colleagues suggests that a much more important negative feedback may now be operating in the Arctic, one which could curb the region's rapid temperature increase and markedly slow the decline in its sea ice. Indeed, it looks strong enough to have an effect on overall global average temperature. This particular negative feedback is driven by the increasing frequency, size and intensity of wildfires in boreal forests. The climate models that scientists use to simulate warming over the coming century run on scenarios that assume these fires will continue more or less as they did in the 2000s and early 2010s. Since then, though, they have become considerably larger. Where there is fire, there is smoke. Some is sooty and dark; some is lighter. Dr Blanchard-Wrigglesworth and his colleagues think that the brighter, more reflective smoke wins out, cooling the ground below. Taking the fire-trend into account, they reckon that, in the 2030s, the extent of sea-ice cover in the Arctic ocean will be at least 3m square kilometres more than it would be in a fire-trend-free model. Without the fire trend, an ice-free Arctic September would be expected in 2050. Fires delay its onset by over a decade. None of this says that the fires are a good thing, or that they will avert catastrophes elsewhere. Fires are a massive shock to ecosystems, and smoke which reflects sunlight also harms humans and other animals. Moreover, the carbon that fires release will warm the entire planet for some time to come. That is clearly bad news. Curious about the world? To enjoy our mind-expanding science coverage, sign up to Simply Science, our weekly subscriber-only newsletter.
National Observer
06-06-2025
- Science
- National Observer
Canada's northern wildfires projected to slow global warming — at a high cost
The climate-driven wildfires currently razing Canada's northern forests and darkening skies across the continent may have an unexpected effect: according to a new study, the fires may reduce global warming and sea ice melt in the Arctic. The rising impact of blazes in Canada and Siberia's boreal regions over the next 35 years will slow warming by 12 per cent globally and 38 per cent in the Arctic, according to recent climate modelling research at the University of Washington (UW). But the study's authors warn that while the study may sound positive, it's just one part of a trend that overall spells major trouble for northern ecosystems. Boreal forest fires affect the climate as smoke particles scatter sunlight back into the atmosphere. These particles, or aerosols, also attract water droplets in clouds making them more reflective — reducing warming trends during the summer in northern areas, said lead author Edward Blanchard-Wrigglesworth, a UW research associate professor of atmospheric and climate science. This effect outweighs other factors like the heat the fires themselves release, or the warming that occurs when black soot falls on white ice or snow, absorbing rather than reflecting sunlight, he said. It also outweighs the planet-heating effect of the carbon dioxide released by the fires. Previous climate models haven't accounted for the increasing scale of wildfire events in boreal forests over the last decade in Canada and Siberia, said co-author Dargan Frierson, a UW associate professor of atmospheric and climate science. The team used the Community Earth System Model (CESM) in the study but hope other climate models and scientists will incorporate the new approach to improve accuracy and understanding of boreal fires impacts, Frierson said. However, while the findings show wildfires mitigate global warming it doesn't significantly change the overall trajectory of the climate crisis, the authors said. The rising impact of blazes in Canada and Siberia's boreal regions over the next 35 years will slow warming by 12 per cent globally and 38 per cent in the Arctic, according to recent climate modelling research at the University of Washington (UW). 'It's an oversimplification to call the study a good news story because large boreal fires still have severely negative impacts on human health and on forest biodiversity,' Blanchard-Wrigglesworth said. 'The most significant takeaway of the study is that how boreal forest fires evolve in the next few decades matters for climate, especially in northern regions, and that we need to better understand the process.' If the intensity of boreal fires drops naturally, or due widespread fire suppression or the climate cooling effect would likely fade within a few years, Blanchard-Wrigglesworth said. 'We need to do more research to address this question,' he said. Warming in other regions like the tropics or southern hemisphere where some of the most severe climate change impacts are expected won't be significantly buffered by boreal fires, he added. 'The primary cause of climate change is the burning of fossil fuels, which remains the primary driver in our new simulations and still drives significant warming,' Blanchard-Wrigglesworth said. Frierson agreed, saying the study results don't reduce the need to slash carbon pollution as fast as possible. The cooling effects of boreal wildfires only slow the runaway truck of climate change, Frierson said, noting wildfires carry huge costs for people and wildlife that aren't captured in the study. The scale of boreal wildfires like those Canada experienced in 2023, when more than 15 million hectares were razed and 200 communities had to be evacuated, bordered on 'apocalyptic,' Frierson said. Smoke from Canadian wildfires this season is already reaching Europe, prompting air quality alerts in the US, and displaced thousands of people in Alberta, Saskatchewan and Manitoba. 'These [boreal fire] impacts that lead to less warming actually happen due to pretty catastrophic situations,' Frierson said. 'We need to take even more rapid action on climate, because that's the only way to get rid of both the fires and much more significant warming.'
