Global Warming : Have we really crossed the 1.5 degrees Celsius limit?

Global Warming : Have we really crossed the 1.5 degrees Celsius limit?

KAKALI DAS

1.5 degrees Celsius – this number is everywhere. It represents a crucial climate threshold, aimed at shielding us from the most severe impacts of a warming planet. Yet, recent headlines suggest we may have already crossed it.

So, what does 1.5 really mean for our world, and for us? Have we already breached this limit? And is it too late to keep the goal of 1.5 alive?

The answer Is complex. No, we haven’t permanently crossed the 1.5°C threshold yet. Yes, global heating has reached dangerous levels. But no, it’s not game over.

The 1.5°C mark refers to the maximum allowable rise in the Earth’s average temperature compared to pre-industrial levels. This target is a critical benchmark to avoid the worst effects of climate change.

Although small island nations had long advocated for this limit, it only gained global attention in 2015 when it was officially included in the Paris Climate Agreement – landmark deal signed by nearly every country on Earth. The agreement aims to keep global temperature rise well below 2°C and to pursue efforts to limit the increase to 1.5°C above pre-industrial levels.

However, political instability continues to pose challenges. Recently, former U.S. President Donald Trump announced that the United States would once again withdraw from the agreement, undermining global cooperation.

The 2 degrees Celsius target is the main goal of the Paris Agreement, while 1.5 degrees is the more ambitious benchmark, both aimed at keeping our planet as liveable as possible.

Since the Paris Agreement was adopted, extensive research has deepened our understanding of these climate limits. And the more we’ve learned, the clearer it’s become: limiting warming to 1.5°C would significantly reduce harm to people and ecosystems compared to 2°C.

If we overshoot 1.5°C and the world warms by 2°C instead, the consequences become far more severe. It could mean more than twice as many people exposed to extreme heatwaves every five years. It could double the number of plant and animal species facing habitat loss. And it would significantly reduce yields of key crops like wheat and maize, threatening food security.

In short, 1.5°C of warming is harmful — but 2°C is far worse. And for the world’s most vulnerable — including low-lying communities and ecosystems — that difference could be a matter of survival. For instance, tropical coral reefs, already struggling under current temperatures, could disappear entirely at 2°C, wiping out one of the planet’s most precious and life-sustaining ecosystems.

A 2°C rise could trigger sea level increases that may annihilate low-lying island nations, a stark reality that explains why these countries fought so hard to establish the 1.5°C limit in the first place.

That’s why keeping global temperatures below 1.5°C is so critically important.

So, have we already crossed that threshold?

Well, 2024 was more than 1.5°C warmer than pre-industrial levels, a milestone so significant that seven independent organizations tracking global temperatures sounded the alarm simultaneously.

But even with such alarming headlines, this doesn’t mean we’ve officially passed the 1.5°C limit.

Let’s go back to the Paris Agreement. It states that the world must “pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels.”

But what does that actually mean?

First, it’s important to understand that the agreement refers to the global average temperature, that is, the temperature averaged across the entire planet.

However, the Paris text isn’t very specific beyond that. It doesn’t define exactly how or when we determine that the limit has been breached, and that’s part of the problem.

Because Earth’s temperature doesn’t rise in a perfect, straight line. Some years are hotter than the last, and some are a bit cooler. But the overall trend is unmistakably upward, and that’s what global warming is all about.

But because of these year-to-year fluctuations, the big question is: when do we actually say the 1.5°C limit has been passed?

Is it when a single year exceeds the threshold? If so, then yes, 2024 did surpass it.

What if it’s based on a single month? That might take us back to January 2016.

And if we consider a single day, then we crossed 1.5°C even earlier, as far back as November 2015, according to ERA5 data – before the Paris Agreement was even finalized.

But here’s the issue: it doesn’t make sense to use just one hot day, month, or even year to declare that we’ve crossed the limit.

Global temperatures fluctuate. A freakishly hot day, month, or year can push us past the threshold, and then temperatures might dip again. These short-term spikes don’t tell the whole story.

Even though 2024 was above the 1.5°C threshold, current scientific consensus suggests it was likely an exceptionally hot year, influenced by temporary factors like El Niño.

That’s why it’s more meaningful to focus not on isolated moments, but on the overall pattern – the long-term trend in rising temperatures.

There are different ways to measure long-term temperature trends, but most projections suggest we’re on track to permanently exceed the 1.5°C limit around 2030, or even sooner if the extreme heat of recent years signals that warming is accelerating.

So no, we haven’t officially passed the 1.5°C limit yet. Even the organizations that announced 2024 was more than 1.5°C warmer than pre-industrial levels agree: the threshold hasn’t been definitively crossed.

However, the fact that we’ve now spent an entire year above the limit is a major warning sign.It shows we are dangerously close. And that, in itself, is deeply concerning.

But timing isn’t the only fuzzy part of the Paris Agreement. Another big question is: what exactly does “pre-industrial” mean?

Defining “pre-industrial” precisely is tricky. When exactly did the Industrial Revolution begin? And how do we accurately measure global temperatures from that time?

Unfortunately, the Paris Agreement doesn’t offer a clear definition.

In practice, climate scientists typically use the period 1850 to 1900 as the pre-industrial baseline. That’s because this period has reliable, consistent temperature records from across the planet, making it a scientifically sound point of comparison.

And since this baseline is used in authoritative sources like the IPCC reports, it has also become the de facto standard for policy discussions.

As long as science and policy are aligned in what they’re referring to, it gives us the clarity we need to ensure that climate action translates into real-world impact.

To stop global warming, we need to stop emitting greenhouse gases. That means decarbonizing everything – our electricity systems, industries, transport, and dramatically reducing emissions from food production and land use.

While we’ve started to bend the emissions curve, global emissions still aren’t falling, let alone falling fast enough to meet the 1.5°C target. To stay within that limit, emissions would need to drop by around 9% every year.

To put that into perspective: that’s about twice the reduction we saw during the COVID-19 lockdowns in 2020, but sustained, year after year.

It sounds daunting, but it’s not physically impossible. With the right policies, investments, and societal will, it can be done.

And here’s something important to understand: nothing dramatic happens the moment we pass 1.5°C. The world doesn’t suddenly plunge into catastrophe.

Instead, the impacts of warming intensify gradually.

There’s barely any difference between 1.499°C and 1.501°C, but 1.6°C is worse than 1.5°C, and 1.7°C is worse still.

Every fraction of a degree matters, and every fraction we can avoid will save lives and ecosystems.

But what about the tipping points, those thresholds where the climate could suddenly and irreversibly change?

It’s true, they’re real. But there isn’t just one single tipping point, and they don’t all get triggered right at 1.5°C.

These tipping points are complex and varied. Some, like a major disruption in ocean circulation or the potential collapse of the West Antarctic Ice Sheet, could occur at different levels of warming, and in different ways.

Some may take place gradually, while others could be more abrupt. What’s crucial is that the risk of triggering them increases with every degree of warming.

We know that crossing the 1.5°C threshold doesn’t suddenly trigger all tipping points at once. Instead, the more we heat the planet, the greater the risk of crossing multiple tipping points.

Climate scientists have different views on how we should talk about 1.5°C, but one thing is clear: this number matters deeply.

It’s also important to pause and reflect on the word “we.” Different people contribute to climate change in different ways, and they experience its impacts very differently as well. Some will continue to make record profits from fossil fuels even after we pass 1.5°C, while others’ lives and livelihoods have already been devastated long before that point.

But even worse scenarios loom. Our best current estimates suggest we are on track for around 3°C of warming by the end of this century, with even more heating possible beyond that. While we desperately want to avoid those futures, they remain a very real risk.

No matter how you look at the 1.5°C target, one thing is undeniable: we’re headed for far too much warming.

So what can we do now?

It may be possible to cool the planet in the future, but we know with certainty that doing so would be extremely difficult and costly.

That’s why we must prioritize what we should have been doing all along, using the tools and solutions we already have to cut emissions as rapidly and deeply as possible.

That means phasing out fossil fuel power plants and replacing them with renewables and nuclear energy. It means transforming our farming systems, especially reducing reliance on animal agriculture and cattle farming. It means electrifying transport wherever possible. These are just some of the many changes the world clearly isn’t implementing fast enough, and I understand how hearing that can feel overwhelming and make you feel helpless.

But it’s vital to remember: we are not powerless. There are big things we can do as individuals working together to build momentum for the structural shifts the world desperately needs.

We can raise our voices to those in power, whether in politics or industry, and demand meaningful change. We can reflect on our own carbon footprints, especially those of us who are relatively well-off or live in wealthier countries. And we can amplify the conversation by talking openly about climate change with people around us and sharing accurate information.

So, to sum up: Last year was more than 1.5°C hotter than pre-industrial levels, but we haven’t officially passed the 1.5°C limit yet. Crossing 1.5°C doesn’t mean the world suddenly ends.It’s a warning sign that climate action is falling short.

The hotter things get, the more people’s worlds will be shattered. So, we cannot give up now. In fact, the lesson here is the exact opposite: the need for urgent action has never been greater.

And if that action feels hard to imagine, I get it. But here’s how the world could realistically reach net zero.

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