In 2024, global climate trends are cause for both deep alarm and cautious optimism. Last year was the hottest on record by a huge margin and this year will likely be hotter still. The annual global average temperature may, for the first time, exceed 1.5°C above pre-industrial levels—a threshold crucial for stabilizing the Earth's climate.

Without immediate action, we are at grave risk of crossing irreversible tipping points in the Earth's climate system. Yet there are reasons for hope.

Global greenhouse gas emissions may peak this year and start falling. This would be an historic turning point, heralding the end of the fossil fuel era as coal, oil and gas are increasingly displaced by clean energy technologies.

But we must do more than take our foot off the warming accelerator—we must slam on the brakes. To avoid the worst of the climate crisis, global emissions must roughly halve by 2030. The task is monumental but possible, and could not be more urgent. It's not game over—it's game on.

Our planet in peril

Last year, Earth was the hottest it's been since records began. The onset of El Niño conditions in the Pacific Ocean helped drive global temperatures to new heights. The European Union's Copernicus Climate Change Service found 2023 was 1.48°C warmer than the pre-industrial average.

Warmer global temperatures in 2023 brought extreme events and disasters worldwide. They included deadly heat waves in the northern hemisphere summer, devastating wildfires in Canada and Hawaii, and record-breaking rains in many places including Korea, South Africa and China.

Last year was also the warmest on record for the world's oceans. More than 90% of heat from global warming is stored in the world's oceans. Ocean temperatures are a clear indicator of our warming planet, revealing a year-on-year increase and an acceleration in the rate of warming.

The warming oceans meant for parts of 2023, the extent of sea ice in the Earth's polar regions was the lowest on record. During the southern hemisphere winter, sea ice in Antarctica was more than one million square kilometers below the previous record low—an area of ice more than 15 times the size of Tasmania.

This year may be hotter still. There is a reasonable chance 2024 will end with an average global temperature more than 1.5°C above pre-industrial levels. Governments have agreed, through the Paris Agreement, to work together to limit global warming to 1.5°C, because warming beyond this threshold poses enormous dangers for humanity.

The agreement refers to long-term trends in temperature, not a single year. So breaching 1.5°C in 2024 would not mean the world has failed to meet the Paris target. However, on long-term trends we are on track to cross the 1.5°C limit in the early 2030s.

As the planet warms, we are now at grave risk of crossing irreversible "tipping points" in Earth's climate system—including the loss of polar ice sheets and associated sea-level rise, and the collapse of major ocean currents. These tipping points represent thresholds which, when crossed, will trigger abrupt and self-perpetuating changes to the world's climate and oceans. They are threats of a magnitude never before faced by humanity—one-way doors we do not want to go through.

This article is republished from The Conversation under a Creative Commons license. Read the original article.