There is growing skepticism of the value of expertise and science, according to a 2023 Pew Research Center study.

While cynicism and snake oil are not new, the ease with which one can “(re)search” a topic is unique to our time.

But even with all the information at our proverbial fingertips, there is an increasing tendency among some people — including in positions of extraordinary power — to compare and equate opinion with scientific evidence.

This phenomenon is evident when it comes to climate change. In a recent series of commentaries in Noozhawk, Michael Rattray questions the validity of human-driven climate change.

Even more troubling, the author casts doubt on whether we should really do anything about it.

Climate change is a matter of fact, not opinion. As UC Santa Barbara scientists and scholars who study the causes and consequences of climate change, we think it is pertinent to provide a more representative perspective on the scientific approach and understanding of climate change.

Scientific Method

The scientific method is the cornerstone of how we rigorously study and understand the world: Observation, testing, prediction, repeat.

These steps may seem simple enough, but they can take months, years and even decades to complete.

But the key is evidence moving beyond opinion, where a simple hypothesis becomes a full-blown theory.

Theory in science, unlike in everyday speech, means a concept so supported by massive amounts of evidence that it is essentially fact. A theory in science is the opposite of a hunch.

Scientific theory is especially rooted in that last step: repeat. In science, we are constantly testing the same or related theories, over and over, and over again, either through replication or through different approaches.

In addition, we have the scientific peer-review process in which other scientists not involved in a given study review the strength of the evidence, approaches and conclusions.

This process takes months to complete. Thus, it involves building vast amounts of evidence over time and space; it is not just someone’s opinion or the result of a Google search.

So, there is no debate in science when it comes to the existence of climate change because an opinion does not hold the equivalent weight to the mountain of science.

Human-Driven Climate Change

Now that we are all on the same page regarding the scientific method, let’s talk about the scientific evidence of climate change driven by human activities.

In his commentaries, Rattray questions the validity of the Intergovernmental Panel on Climate Change (IPCC) reports, which have been updated and released every five years since 1990.

He is correct that there are three working groups; however, the depth and extent of the coverage of the United Nations-assembled efforts on climate change were sorely overlooked and mischaracterized.

Working Group I: assesses the physical science of climate change (12 chapters, 2,409 pages)

Working Group II: assesses the vulnerability of socioeconomic and natural systems to climate change, negative and positive consequences of climate change, and options for adapting to it (18 chapters, 3,675 pages)

Working Group III: focuses on climate change mitigation, assessing methods for reducing greenhouse gas emissions, and removing greenhouse gases from the atmosphere (17 chapters, 2,042 pages)

Hundreds to thousands of volunteer scientists who study climate change contribute and coordinate to their respective working groups and chapters over several years.

Each respective working group report pulls together all the foundational and updated science on the associated topics (e.g., agriculture) and regions (e.g., North America) contained in each document that is thousands of pages long, documenting the collective, repeated and diverse pieces of evidence.

This includes models projecting changes in temperature, the paleoclimate data from ice cores tracing CO₂ concentration back hundreds of thousands of years, and shifts of species we are witnessing in real time.

There is also the traceability documentation, FAQs, fact sheets, technical summaries and summaries for policymakers to help distill the main findings of these lengthy, exhaustive and rigorous reports.

We would also be remiss if we did not highlight the U.S. government’s mandated National Climate Assessment, as well as California’s own Climate Change Assessment.

IPCC efforts operate at the global scale, while the national and state assessments provide deeper insights and finer resolution of climate change consequences at those respective scales. (We have provided links to the main reports in case readers want to dive into the vast accumulation of evidence themselves.)

All of this is to say, lack of data is not the problem. The challenge lies in what we choose to do with this vast accumulation of reliable information.

This is a question of policy and ethics.

Impacts and Solutions

A few core truths have emerged from decades of research on our climate system.

First, human emissions of greenhouse gases (primarily CO₂, but also methane, nitrous oxide and several others) have significantly increased atmospheric concentrations of these gases.

Second, these increases are causing measurable planetary warming and are projected to continue warming the planet over the coming decades.

In fact, in 1856, physicist Eunice Foote identified the linkage between CO₂ and a warming atmosphere, and in the 1970s even ExxonMobil linked and projected fossil fuel emissions to a warming planet.

Third, we are already witnessing impacts, and projected changes are going to be disruptive to our societies.

Here in California, droughts are becoming more punctuated, exacerbating limited water resources for our food production and increasing wildfire risk.

As a result of these growing threats insurance companies are already choosing not to insure homes in areas deemed too risky.

In fact, Zillow has a “climate risk” feature to help potential buyers make informed housing market choices. These companies know and trust the science and are acting on its predictions now.

Ignoring these truths slows our very real ability to act.

What is up in the air is how human societies choose to respond to greenhouse gas emissions and climate change.

Not acting remains a policy choice. Acting, too, is a choice, and one that involves complex and challenging options and impacts.

Alternative energy strategies — such as solar, offshore wind and electric cars — are key; they, too, come with price tags and environmental impacts.

However, it is the strong consensus of the scientific analyses that the price of inaction is greater. In the United States alone, extreme weather and climate disasters have cost the nation thousands of human lives and nearly $3 trillion since 1980.

But we have the option to carry out policies that would reduce future projected impacts.

Optimistically — a view that sometimes gets lost in “doomerism” — the worst of the climate forecasts are in fact not locked in.

The curve toward carbon neutrality and climate stability has already been bent due to policy changes and technological shifts, and we can bend it further with policies that significantly reduce greenhouse gas emissions (Figure 2 in the nearby illustration). Every degree counts.

Finally, there are other kinds of evidence worth considering. The evidence of climate change’s impacts is often most readily observed in the real-world, day-to-day experiences of people living with the consequences.

In the United States and around the globe, those facing the disproportionate brunt of climate harms include low-income people, people of color, women, disabled persons, LGBTQ+ communities and Indigenous communities.

For decades, these populations — many of whom contribute the least amount of greenhouse gas emissions — have confronted the worst dimensions of our climate crisis. They have been proposing solutions to mitigate and adapt to these challenges.

Many scientists and scholars have concluded that we can learn a great deal from their experiences.

Rational debates on the costs and benefits of different policy strategies — distinct from debating climate change itself, which is consensus science — depend upon accepting the facts as they stand.

The IPCC reports represent humanity’s best evolving understanding of the climate science. We cannot hold meaningful debates about climate science and policy on the basis of opinion.

Our children will hold us responsible for the world we leave them. We owe them the courage to confront the facts.