New York City is choking on smoke from hundreds of wildfires ravaging Canadian forests. The sun rose ominously over the city on Tuesday morning, a fiery red orb obscured by the poisonous fog — as if the sky was sending a message: the climate crisis is in code red.

This eerie reminder of the need for urgent climate action cast a hazy shadow over the ambition, optimism and celebrations of World Environment Day, which concluded just hours before residents awoke to the cloud of pollution that continues to engulf New York City.

Canadian forestry officials reported over 400 active wildfires as of Wednesday afternoon, with more than 240 listed as “out of control”. Over 400 wildfires have scorched the forests of Quebec alone since the start of the year, double the average for the mid-year mark.

Wildfire smoke can be deadly. It contains tiny particles, or PM2.5, that can travel deep into the lungs and bloodstream, causing a variety of health problems, including asthma, heart disease, and respiratory illnesses. The particles come from sources such as the combustion of fossil fuels, dust storms, and wildfires. The resulting air pollution kills nearly 7 million people every year.

At its peak, the smoke over New York City contained 142.6 micrograms of PM2.5 per cubic meter of air – nearly 30 times the World Health Organization’s safe air quality guideline. On Tuesday evening, the air quality in the city briefly surpassed New Delhi as the world’s most polluted in any major city.

New Delhi’s air pollution caused over 50,000 premature deaths in 2020, a small fraction of the total of 1.6 million across India. The air pollution crisis in India’s major cities has led to the rise of a so-called “pay-to-breathe” industry, where the ability to afford expensive air purifiers can determine whether residents stay safe from the smog, driving a new kind of life-or-death inequality.

Cities on the east coast of North America are not in danger of catching up to New Delhi or Mumbai in year-round air pollution, but climate change is set to make the occurrence of PM2.5 spikes more frequent and more dangerous for human health.

Warming global temperatures caused by human activity have intensified the hot and dry seasons when wildfires thrive. Scientists say carbon pollution from fossil fuel and cement companies is directly responsible for millions of acres of wildfires across the North American west coast.

And far from the skyscrapers of New York City, an invisible threat is growing: melting ice in the Arctic.

‘Arctic Amplification’

Arctic sea ice is melting rapidly, shrinking at a rate of 12.6% every decade, according to NASA. Arctic temperatures have also increased four times faster than those in the rest of the world.

Yet a summer without sea ice in the Arctic was not projected to happen until at least the middle of the century. In its 2021 assessment report, the UN Intergovernmental Panel on Climate Change (IPCC) calculated the Arctic would only reach an ice-free state around 2050 under “intermediate and high greenhouse gas emissions scenarios”.

Scientists now project that milestone could be reached as early as the 2030s under a business-as-usual emission scenario. Even if emissions are cut drastically – a target the world is far from achieving – the melting of the sea ice in the Arctic cannot be stopped, the study found.

“The Arctic Ocean will become sea ice-free in September for the first time before 2050, irrespective of emissions scenarios,” the peer-reviewed study published in Nature Communications on Tuesday said.

It is now too late to save summer Arctic sea ice, research has shown, & scientists warn preparations need to be made for the increased extreme weather across the northern hemisphere that's likely to occur as a result https://t.co/PHIU6XOuAQ #ClimateCrisis 🚨

— Carbon Tracker (@CarbonBubble) June 6, 2023

The absence of Arctic sea ice will affect weather patterns and sea-level rise around the world.

The white ice reflects sun rays back into space. As the ice melts, more heat is absorbed by the dark waters of the ocean, creating a feedback loop known as “Arctic amplification”.

As the Arctic warms, the temperature difference between the North Pole and the Equator – a major force driving global weather patterns – increases. This could have dire consequences for the frequency of extreme weather events such as floods, heatwaves and resulting wildifres across the temperate regions of North America, Europe and Asia.

“We need to prepare ourselves for a world with a warmer Arctic very soon,” Seung-Ki Min, a lead author of the study and a climate scientist at Pohang University of Science and Technology in South Korea told CNN. “Our result suggests that the Arctic amplification will be coming faster and stronger. That means the related impacts will also be coming faster.”

Vanishing sea ice in the Arctic will also accelerate the melting of the Greenland ice sheet, with major effects on sea-level rise globally.

Image Credits: National Weather Service, Annie Spratt.