The big climate change debate

I have had the pleasure of reading a number of comments on my articles, with a good number suggesting that climate change doesn’t exist, if it does, it’s part of the Earth’s natural cycles, or because we are getting further from the ice age, hence the global warming.

Some of the lines appear to be aimed at comforting to some by shifting responsibility away from human behaviour. However, comfort is not evidence.

It all sounds familiar, but it’s reason enough to continue writing and educating.

The scientific picture is unambiguous: Earth is warming fast, the rise in heat and greenhouse gases is driven by human activity.

The kind of natural cycles invoked by sceptics — the slow orbital wobbles that bring ice ages and interglacials — operate on timescales and with fingerprints completely different from what we are seeing today.

The conclusions are not the product of political opinion but of decades of observations, theory and careful attribution by many independent groups of scientists.

Let’s start with the measurements.

The long-running Mauna Loa Observatory record and other monitoring stations show atmospheric carbon dioxide — the primary heat-trapping gas produced when we burn fossil fuels — rising from about 280 parts per million (ppm) in pre-industrial times to well over 400 ppm today.

That jump is not trivial: it represents a fundamental change in the composition of the atmosphere, and it correlates tightly with industrial emissions.

The trend is accelerating. Recent years have seen record annual increases in CO₂ and other greenhouse gases.

Those rising concentrations are not compatible with a hypothesis that current warming is merely a slow, benign return to some natural baseline. This is science based on empirical evidence, not suppositions.

Second, the physics is straightforward and well tested. Greenhouse gases trap outgoing infrared radiation; add more of them and the planet’s energy balance changes.

Climate models built on that physics successfully reproduce the observed warming only when human emissions are included.

They fail to do so when forced with natural factors alone, such as solar variability, volcanic eruptions, orbital changes.

Observations also show the expected “fingerprints” of greenhouse warming, for example, the troposphere (lower atmosphere) warming while the stratosphere cools, and nights warming faster than days — patterns that are predicted by an enhanced greenhouse effect but not by, say, increased solar output.

These are not speculative claims: they are observed, quantifiable features that match the mechanisms scientists describe.

What about Milankovitch cycles — the orbital changes that historically paced ice ages?

Recent dominant drivers of global warming is human activity

These certainly shape Earth’s climate over tens to hundreds of thousands of years, but they operate on slow time scales and produce changes in the distribution of sunlight, not the global, rapid swings we’ve measured in the last century.

Importantly, satellite measurements show that solar irradiance has not increased over recent decades in a way that could explain the rapid warming. In fact, solar output has slightly declined while temperatures have risen.

The timing and pattern of recent warming simply do not match what orbital cycles would produce. Invoking them to explain the dramatic rise in global temperatures is like blaming a ticking grandfather clock for a sudden heatwave.

Sceptics sometimes point to natural variability — El Niño, volcanic eruptions, or multidecadal oscillations — and indeed, those influence year-to-year weather and can temporarily amplify or dampen warming.

But variability sits on top of a clear upward trend.

Attribution studies, which use physics-based models and observations to separate causes, consistently find that the dominant driver of the warming since the mid-20th century is human activity.

This is from the burning of coal, oil and gas, widespread deforestation and industrial agriculture that releases methane and nitrous oxide.

The Intergovernmental Panel on Climate Change (IPCC), synthesising thousands of studies and evidence lines, states that the recent warming is overwhelmingly the result of human influence.

That is not a political or economic consensus but a scientific one grounded in multiple, independent datasets and methodologies.

What every tonne of carbon released means

Facts matter because they determine the risks we face. If warming were purely natural and transient, policy responses might focus on adaptation alone.

But when the driver is the emissions we can control, mitigation becomes urgent.

Every tonne of carbon released today increases the chance of more intense heatwaves, stronger storms, sea-level rise that threatens coastal cities and low-lying nations and the cascade of ecological and social disruptions that follow.

Some of the contributors claim the climate’s Earth has changed several times before with carbon emissions.

Yes, that may be so, but we now know the causes and what is required to fix the problem. Most probably, during those said changes that happened before, science had not developed enough to point to causes and solutions.

In the present-day Earth, we should consider ourselves lucky enough to have science that can point to causes and solutions of warming.

Recent monitoring agencies and meteorological bodies have sounded alarms about record greenhouse gas concentrations and the rising likelihood of extreme events consistent with a warming planet — warnings grounded in measurement, not alarmism.

Responding to climate change is not a gamble

Finally, responding to climate change is not a gamble. It is a risk-management decision based on the best available evidence.

Treating the atmosphere like an experimental lab where we can keep burning ever more fossil fuels and hope for the best, or to see what will happen, is a dangerously short-sighted strategy.

The science does not demand perfection, it asks for honesty and prudence: reduce emissions, invest in resilient infrastructure, and accelerate the shift to cleaner energy to mitigate catastrophe.

Those steps are practical, economically sensible in many cases, and aimed at limiting the harms that the evidence shows are increasingly likely if current trends continue.

Dismissing climate change as “natural” or a relic of an ancient ice-age rhythm ignores both the scale of the perturbation we’ve introduced and the tools that let us read the atmosphere’s response.

Conversations about costs, fairness and the pace of transition are vital — but they must start from the same baseline of facts.

The planet is warming, humans are the dominant cause, and continuing on the current emissions path is a policy choice with clear, measurable risks.

Denial is no longer a refuge of reasonable debate, it is an obstacle to the collective action science shows we need.

Political ideology or financial interests cannot change physics.

• Dr Enock Sithole is the executive director of the South Africa-based Institute for Climate Change Communication.