By Ellie Gabel 
From higher temperatures to stronger storms, the evidence for climate change is clear. Scientists track these patterns through climate change indicators. Recognizing these warning signs is the first step toward taking meaningful action to protect the planet and the creatures living in it.
A climate change indicator is a measurable sign that shows how the Earth’s climate is changing over time. These indicators come from years of scientific data, revealing clear trends and patterns that paint a clear picture of the world and where it’s headed. This information helps researchers and governments understand and address the scope, causes and effects of climate change.
These are the most critical climate indicator categories that scientists are monitoring today.
Since 1850, greenhouse gas emissions have increased exponentially, primarily due to the widespread use of fossil fuels, which, when combusted, produce a significant amount of carbon dioxide and other chemicals.
Greenhouse gases like carbon dioxide, methane and nitrous oxide trap heat in the atmosphere. While they naturally regulate temperature, human activity has pushed their levels beyond normal, causing the greenhouse effect. This phenomenon has resulted in global temperature increases, changing rainfall patterns and other ecosystem disruptions.
The World Meteorological Organization has confirmed that 2024 was the warmest year on record, with the Earth’s surface temperature reaching 34.79°F (1.55 °C) above the 1850-1900 or pre-industrial average.
While this number might seem small, it still has significant consequences. Higher heat levels impact the seasons and increase the risk of wildfires and other climate-related events. In urban areas, people face rising energy costs and increased health risks as heatwaves become more frequent and severe.
Extreme weather has always existed, but it has grown more frequent and intense in recent years. Warm air can fuel stronger storms and heavier rainfall. In dry conditions, it can cause drought and wildfires.
Data shows that the occurrence of extreme weather events has increased fivefold over the past 50 years, comprising 50% of all disasters, 45% of all deaths and 74% of global economic losses.
Clean water is essential to sustaining life on Earth, and climate change is reshaping the water cycle, affecting its availability.
Some areas are experiencing more rainfall and flooding, while others struggle with drought that threatens agriculture and drinking water. Glaciers and snow — once dependable water sources — are melting and shrinking more rapidly than before.
While there are some natural variations in the timing and duration of the seasons each year, climate change is driving more noticeable and longer-term shifts.
Winter temperatures across 48 states have increased by about 3°F, spring temperatures by 2°F and summer and fall temperatures by around 1.6°F. Instead of snow, more winter precipitation is falling as rain. Spring is arriving earlier, with lake ice thawing sooner.
These seemingly small changes result in unpredictable seasonal shifts, leading to agricultural problems and ecosystems going out of sync. Growing seasons become longer, with pests becoming more abundant. These disruptions threaten biodiversity, as species struggle to adapt to the changing environment.
The ocean absorbs around 90% of the excess heat generated by human activities and the greenhouse effect. This phenomenon has led to two dangerous trends — warming and acidification.
Warming waters disrupt baseline ocean temperatures, changing the currents and creating more fuel for stronger storms. Rising ocean temperatures also affect marine ecosystems, disrupting migratory patterns, damaging coral reefs and disturbing existing food chains.
Global sea levels have risen by approximately 111 mm from 1993 to 2023, and the rate of increase is accelerating. This rise comes from melting glaciers and ice sheets and the expansion of sea water as it warms.
Coastal areas, such as South Florida, are already experiencing “sunny day flooding,” where high tides flood streets even without rainfall. If rain does fall, residents suffer more significant floods. Rising seas present a considerable threat to these areas. People might be forced to move or adapt if this trend continues, leaving low-lying regions uninhabitable.
Snow cover has decreased significantly over the decades, while permafrost — frozen ground found in or near the poles — and glaciers are thawing more rapidly than before. As they melt, they move to the ocean, contributing to sea level rise.
Many communities that have settled in permafrost for centuries also risk losing their homes and livelihoods. As permafrost thaws, the ground becomes more prone to erosion, affecting the integrity of homes and other structures.
Recognizing these indicators is half the challenge. The next step is action. While the scale of climate change is vast, there are ways to address it through the support and initiative of key institutions.
Cutting greenhouse gas emissions is one of the most critical steps to halt the worsening of climate change. This effort means transitioning away from fossil fuels and investing in renewable energy sources like solar and wind power.
Businesses and corporations play a significant role, as they are among the largest contributors to carbon emissions. Setting net-zero goals and prioritizing supply chain sustainability can lead to noticeable changes.
Nature is a strong ally against climate change. Oceans, forests, soil and fungi are natural carbon sinks. Protecting and restoring these ecosystems helps improve carbon capture, protect biodiversity and strengthen resilience against floods or droughts.
Some climate impacts are unavoidable. Adaptation is about preparing for what’s already happening. These efforts include improving flood defenses or developing drought-resistant crops. Governments and businesses should establish early warning systems and disaster risk reduction measures to protect lives and economies from potential damage or disruptions.
Lasting progress depends on strong government policy and international cooperation. Climate policies that support clean energy investment and other sustainable practices are essential for large-scale impact.
Every vote, policy endorsement and advocacy effort matters. Collaborating with climate activists and organizations generates public pressure, prompting leaders to prioritize their climate commitments and ensuring that solutions move from discussion to action.
The world’s climate indicators tell a consistent story. The planet is getting hotter and entire ecosystems are under stress, with human activity as the primary driver. However, the same data also presents a clear path forward.
Governments, businesses and civil society all need to prioritize reducing emissions, adopting renewable energy sources and protecting ecosystems. What happens next depends on the actions taken today.
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