More than 1 million fires in Australia detected by satellites since September

Australia’s ruinous fire season can be seen from space. NASA’s satellites have spotted more than a million infrared heat signatures — telltale signs of fires — across the country since the beginning of September.

[Why Australia’s bush fires are so severe]

The fires have largely been concentrated in the southeastern state of New South Wales, home to Sydney, where authorities last week declared a state of emergency for the third month in a row. At least 25 people have died, and the persistent burning has devastated forests, destroyed thousands of homes, and killed millions of animals — more than a billion, by one estimate.

NASA’s satellites, which identify active hotspots by measuring their infrared emissions, have spotted far more fires this season than any since 2013.

The fires have not just been more abundant than previous years. They have also affected the heart of the forest ecosystems in the country’s southeastern coast, where iconic wildlife reside. These forests help support water supplies for the most populated regions of the country, such as Sydney and Melbourne.

Though experts say human-caused climate change is making the fires last longer, grow larger and exhibit extreme fire behavior, Australian Prime Minister Scott Morrison has resisted calls to take stronger measures to reduce greenhouse gas emissions.

In recent years, wildfires have torn across California and the Amazon, killing hundreds of people and torching millions of acres. Yet this season’s fires have covered an even larger area, about the size of West Virginia.

The fire is causing distress beyond Australia’s borders, too. Smoke from the fires has blown eastward across the Tasman Sea, enveloping New Zealand and stretching across the Pacific Ocean to South America.

Invisible chemical compounds are traveling through the air across the Southern Hemisphere. An air pollution satellite run by the European Space Agency has detected increasing levels of carbon monoxide, which can poison people who inhale too much of it.