Tell Me About Climate Change | How Greenhouse Gases Warm Earth and Change Weather, Oceans and Ecosystems

Tell me about climate change. Climate change is a long-term shift in the statistical patterns of Earth’s climate, including temperature, rainfall, ice, oceans, winds and extremes. In the modern era, the dominant driver of observed global warming is the increase in greenhouse gases produced by human activities, especially carbon dioxide from fossil-fuel combustion, land-use change and industry, together with methane, nitrous oxide and other heat-trapping gases.

When people ask how climate change works, the most important mechanism is the greenhouse effect. Earth absorbs energy from sunlight and emits energy back toward space mainly as infrared radiation. Greenhouse gases absorb and re-emit some of that outgoing infrared radiation, reducing the rate at which energy escapes to space. Increasing greenhouse-gas concentrations strengthens this effect, creating an energy imbalance that warms the climate system until outgoing energy rises enough to restore balance.

Climate change is larger than the phrase global warming. Rising average temperature is central, but warming changes evaporation, rainfall, snow and ice, ocean heat, sea level, ecosystems and the likelihood or intensity of some extreme events. Climate scientists study these changes using thermometers, satellites, ocean measurements, ice cores, tree rings, physics-based models and many other independent lines of evidence.

The 50-Second Answer

Sunlight enters the Earth system mostly as visible and shortwave radiation. Earth’s surface and atmosphere absorb part of that energy and later emit infrared radiation. Greenhouse gases such as carbon dioxide, methane and water vapour interact strongly with particular infrared wavelengths, making the atmosphere less transparent to outgoing heat.

Human activities have increased concentrations of long-lived greenhouse gases. The resulting radiative forcing adds energy to the climate system. Most of the excess heat enters the oceans, while the atmosphere, land and cryosphere also warm. Ice melts, sea level rises, evaporation patterns change and many ecosystems shift.

Weather still varies from day to day and year to year. Climate change alters the background conditions and probabilities on top of that natural variability.

Weather Versus Climate

Weather describes short-term atmospheric conditions such as today’s temperature, rain, wind and storms. Climate describes the statistical behaviour of weather over longer periods, often measured across decades. A single cold day does not disprove long-term warming, just as one hot day alone does not prove a climate trend.

The distinction is similar to personality versus mood. A person’s mood can vary from hour to hour, while a longer-term pattern describes something different. Climate statistics include averages, ranges, seasonal patterns, frequencies and extremes.

Scientists detect climate change by analysing sustained changes across many observations rather than interpreting isolated events.

Earth’s Energy Balance

Earth’s climate is governed by energy entering, moving through and leaving the planet. Incoming solar energy is partly reflected by clouds, atmospheric particles, snow, ice and bright surfaces. The rest is absorbed by the atmosphere and surface.

A warm Earth emits infrared radiation. For a stable long-term climate, outgoing energy must approximately balance absorbed incoming solar energy. If less energy leaves than enters, the planet accumulates heat and warms. If more leaves than enters, it cools.

Climate forcing changes this balance. Greenhouse gases, solar variations, volcanic aerosols and surface changes can all alter how much energy is absorbed or emitted.

The Natural Greenhouse Effect

The greenhouse effect is not inherently harmful. Without naturally occurring greenhouse gases, Earth’s surface would be far colder and liquid water would be much less widespread. Water vapour, carbon dioxide, methane, nitrous oxide and clouds help keep the planet warm enough for current ecosystems.

The modern problem is an enhanced greenhouse effect. Human activities add greenhouse gases faster than natural processes remove all of them, raising atmospheric concentrations and strengthening infrared absorption.

The glass-greenhouse analogy is imperfect because an actual greenhouse warms partly by restricting convection. Earth’s greenhouse effect is fundamentally a radiative process involving absorption and emission of infrared energy.

Carbon Dioxide

Carbon dioxide is released naturally by respiration, decomposition, oceans, fires and volcanoes, and removed by photosynthesis, ocean uptake and long-term geological processes. Human activities add additional carbon dioxide by burning coal, oil and gas, producing cement and changing land cover.

Carbon dioxide is important because a substantial fraction remains in the atmosphere for very long periods while the rest moves into oceans and land reservoirs. Its warming effect therefore accumulates with total emissions.

The carbon cycle redistributes added carbon among atmosphere, ocean, vegetation and soils, but it does not remove all human emissions instantly. That is why cumulative emissions matter.

Methane

Methane is a powerful greenhouse gas with a shorter atmospheric lifetime than carbon dioxide. It is emitted from wetlands naturally and from human activities including fossil-fuel production, livestock, rice cultivation, landfills and waste systems.

Methane is gradually removed through atmospheric chemistry, so reducing emissions can affect its concentration and warming influence more quickly than an equivalent strategy focused only on very long-lived gases.

Methane also participates in atmospheric chemistry that influences ozone and stratospheric water vapour, so its climate effects extend beyond direct infrared absorption.

Nitrous Oxide and Other Gases

Nitrous oxide is emitted naturally by soils and oceans and is also increased by agricultural fertiliser use, manure management and industrial processes. It is long-lived and contributes to warming while also affecting stratospheric ozone chemistry.

Fluorinated gases used in refrigeration, electronics and industrial applications can have very high warming potency per molecule, although their concentrations are much lower than carbon dioxide.

Climate forcing depends on concentration, infrared absorption, atmospheric lifetime and interactions with the wider system. No single gas tells the whole story.

Water Vapour: Feedback, Not the Main Initial Driver

Water vapour is the most abundant greenhouse gas in the atmosphere, but its concentration is strongly controlled by temperature because warm air can contain more water vapour. This makes water vapour primarily a feedback in current global warming rather than the main long-term forcing.

When carbon dioxide or another forcing warms the atmosphere, evaporation and atmospheric moisture generally increase. More water vapour then strengthens greenhouse warming, amplifying the original change.

If temperatures fell, atmospheric water vapour would also decline. Long-lived greenhouse gases are therefore especially important because they can initiate and sustain the temperature change that water vapour amplifies.

Radiative Forcing

Radiative forcing is a way of comparing factors that disturb Earth’s energy balance. A positive forcing tends to warm the system; a negative forcing tends to cool it. Added greenhouse gases create positive forcing, while certain reflective aerosols create negative forcing.

The concept helps scientists compare very different influences in a common energy unit. It also separates an initial cause from the climate system’s later responses.

Temperature change depends not only on forcing but also on feedbacks, heat uptake and the timescales over which the atmosphere, ocean, ice and ecosystems respond.

Aerosols

Aerosols are tiny particles or droplets suspended in the atmosphere. Some scatter sunlight back to space and produce cooling, while others such as black carbon absorb sunlight and warm the atmosphere. Aerosols can also change cloud properties, affecting brightness, lifetime and precipitation.

Unlike carbon dioxide, many aerosols remain in the atmosphere for days to weeks rather than centuries, so their climate effects are concentrated near source regions and respond quickly to emission changes. Air-pollution controls can therefore reveal some warming that had previously been masked by reflective particles, even while providing major health benefits.

Climate Feedbacks

A feedback changes the response after an initial forcing. Water-vapour feedback is positive because warming increases atmospheric moisture, which adds warming. Ice-albedo feedback is also positive: melting snow and ice expose darker surfaces that absorb more sunlight.

Cloud feedbacks are more complex because clouds can both reflect sunlight and trap infrared radiation. Their net effect depends on height, thickness, location and microphysics.

Some feedbacks are negative and resist change. A warmer Earth emits more infrared energy to space, which acts as a fundamental stabilising response. Climate sensitivity reflects the combined result of these processes.

Oceans Store Most of the Excess Heat

The oceans have enormous heat capacity and absorb most of the excess energy added to the climate system. This slows atmospheric warming but commits the planet to continued ocean change.

Ocean heat content is therefore one of the clearest indicators of planetary energy imbalance. Warming penetrates from the surface into deeper layers through mixing and circulation, though not uniformly everywhere.

Warmer oceans influence marine ecosystems, sea level, stratification, oxygen levels and the energy available to some weather systems.

Sea-Level Rise

Global mean sea level rises mainly for two reasons: seawater expands as it warms, and land ice melts and adds water to the ocean. Mountain glaciers and the Greenland and Antarctic ice sheets all contribute.

Melting sea ice does not raise sea level much directly because floating ice already displaces water, though sea-ice loss affects climate through albedo and ecosystems. Land ice is different because its meltwater enters the ocean from continents.

Local sea level can differ from the global mean because land itself may rise or sink, ocean circulation changes and gravitational effects redistribute water.

Glaciers and Ice Sheets

Glaciers gain mass through snowfall and lose it through melting, sublimation and ice flow. Persistent warming can push their mass balance negative, causing retreat and thinning. Glaciers provide water storage for many mountain regions, so their changes affect downstream systems.

Ice sheets respond over longer timescales but contain enough ice to influence sea level dramatically. Surface melting, ice-shelf changes, ocean-driven melting at grounding lines and faster ice flow can all contribute.

Ice-sheet physics includes thresholds and long response times, making some future changes difficult to reverse quickly even if temperatures later stabilise.

Arctic Amplification

The Arctic has warmed faster than the global average, a pattern known as Arctic amplification. Sea-ice loss exposes darker ocean surfaces that absorb more sunlight, while changes in snow, clouds, atmospheric temperature structure and heat transport also contribute.

Arctic warming affects ecosystems, permafrost, coastal erosion and human communities. It can also influence atmospheric and oceanic circulation, though specific links to mid-latitude weather vary by mechanism and remain active research topics.

The important lesson is that global warming is not spatially uniform. Regional responses can be much larger or smaller than the global average.

Permafrost

Permafrost is ground that remains frozen for at least two consecutive years. It stores large amounts of organic carbon accumulated under cold conditions. As permafrost warms and thaws, microbes can decompose previously frozen organic matter, releasing carbon dioxide and methane.

Thaw also changes landscapes. Ground can collapse where ice-rich soil melts, damaging roads, buildings and ecosystems. Lakes can form or drain, vegetation changes and hydrology reorganises.

Permafrost carbon is therefore a feedback: warming can unlock additional greenhouse-gas emissions that reinforce warming.

Climate Tipping Elements

Some parts of the climate system may contain thresholds beyond which change becomes self-sustaining or much harder to reverse. Scientists study potential tipping elements including ice sheets, major ocean-circulation systems, tropical forests and permafrost regions.

A tipping point does not mean the whole planet instantly flips into a new state on one date. Different systems have different thresholds, timescales and uncertainties. Crossing a threshold can instead commit a component to long-term change that unfolds over decades or centuries.

The concept matters because risk can rise nonlinearly: an additional amount of warming may have a larger consequence if it moves a vulnerable subsystem closer to an unstable regime.

The Carbon Cycle

The carbon cycle moves carbon among the atmosphere, oceans, living organisms, soils, sediments and rocks. Photosynthesis removes carbon dioxide from the atmosphere, while respiration and decomposition return it. Oceans exchange carbon dioxide with the air and store vast amounts in dissolved forms.

Fossil fuels contain carbon stored over geological time. Burning them transfers that carbon rapidly into the active atmosphere-ocean-land system. Land clearing can also release carbon from vegetation and soils while reducing future uptake.

Natural sinks currently absorb a substantial share of human emissions, but their efficiency can change as climate, ecosystems and ocean chemistry change.

Ocean Acidification

When carbon dioxide dissolves in seawater, it reacts with water to form carbonic acid and shifts the balance of dissolved carbonate chemistry. This lowers ocean pH, a process called ocean acidification.

Acidification is chemically distinct from warming even though both are driven partly by rising atmospheric carbon dioxide. Lower carbonate-ion availability can make it more difficult for some organisms to build calcium-carbonate shells or skeletons.

The effects vary among species and ecosystems, but coral reefs and some shell-forming organisms are particular concerns because they face multiple stresses simultaneously.

Coral Reefs

Corals live in partnership with photosynthetic algae that provide much of their energy. Excessive heat can disrupt this relationship, causing bleaching as corals lose the algae or their pigments. Bleached corals are stressed and can die if unfavourable conditions persist.

Ocean acidification can further challenge reef building, while pollution, overfishing and disease add local stresses. Reef outcomes therefore depend on both global climate pressures and local management conditions.

Because reefs support biodiversity, fisheries and coastal protection, their response to warming has consequences far beyond the coral organisms themselves.

Rainfall and the Water Cycle

A warmer atmosphere can hold more water vapour, and warming increases evaporation in many regions. This intensifies parts of the water cycle, but it does not mean every place becomes wetter.

Atmospheric circulation, topography, storm tracks and soil feedbacks determine regional rainfall. Some areas experience heavier precipitation, while others face longer dry periods or shifts in seasonal timing.

Climate change therefore redistributes water risk. Flood and drought can both become concerns, sometimes in the same region at different times.

Heatwaves

When the average temperature distribution shifts upward, very hot conditions become more likely even before considering other regional changes. Heatwaves can also be intensified by dry soils, persistent high-pressure systems and urban heat effects.

Extreme heat affects human health, agriculture, infrastructure, labour productivity and ecosystems. Night-time temperatures matter because warm nights reduce recovery from daytime heat.

Attribution studies can estimate how climate change altered the probability or intensity of a particular heat event by comparing models of the present climate with simulations of a world without the relevant human forcing.

Heavy Rain and Flooding

Warmer air can contain more water vapour, giving storms access to greater moisture. This physical relationship contributes to increases in heavy precipitation in many regions.

But flooding depends on more than rainfall. Soil saturation, river engineering, drainage, land cover, tides, snowmelt and urban surfaces all influence whether water becomes destructive.

Climate change can therefore alter one part of flood risk while local development determines exposure and vulnerability.

Drought

Drought can refer to lack of rainfall, low soil moisture, reduced streamflow or shortages relative to water demand. Climate change can influence each through different mechanisms.

Higher temperature increases evaporative demand, so soils can dry faster even if rainfall changes only modestly. Snow can melt earlier, shifting seasonal water availability. Changes in circulation can alter how often dry weather patterns persist.

Because drought has multiple definitions, scientific claims should specify the region, timescale and drought metric being discussed.

Tropical Cyclones

Tropical cyclones draw energy from warm ocean water and depend on atmospheric conditions such as humidity and wind shear. A warming climate changes several of these ingredients.

Research indicates that the strongest storms can become more intense and produce heavier rainfall in a warmer climate, while regional changes in storm frequency and tracks are more complex. Sea-level rise also increases the baseline on which storm surge acts.

It is therefore better to ask how climate change affects storm intensity, rainfall and coastal impact than to claim that every individual cyclone is simply “caused” by climate change.

Wildfire

Wildfire requires fuel, ignition and weather conditions that allow burning. Climate change can increase fire-conducive conditions in some regions by raising temperatures, drying fuels and lengthening fire seasons.

Land management, vegetation history, ignition sources and settlement patterns also strongly affect fire risk. Some ecosystems evolved with frequent fire, while others are highly vulnerable to unusually intense burning.

Climate science therefore treats wildfire as an interaction among weather, ecosystems and human land use rather than one-variable causation.

Ecosystems and Species

Species respond to climate through range shifts, migration timing, flowering, breeding, growth and survival. Some move poleward or upward in elevation as temperatures change. Others cannot move fast enough because habitats are fragmented or suitable environments disappear.

Ecological relationships can become mismatched. A plant may flower earlier while its pollinator responds differently. A predator’s range may shift into contact with new prey. Coral bleaching can restructure entire reef communities.

Climate change acts alongside habitat loss, pollution, invasive species and harvesting, so biodiversity outcomes reflect multiple interacting pressures.

Agriculture and Food

Crop growth depends on temperature, water, carbon dioxide, nutrients, pests and extreme events. Elevated carbon dioxide can stimulate photosynthesis in some plants under suitable conditions, but heat stress, drought, flooding, nutrient limitations and pests can offset or reverse benefits.

Different crops and regions therefore face different outcomes. Farmers can adjust planting dates, varieties, irrigation and management, but adaptation has limits where warming or water stress becomes severe.

Food systems also depend on storage, transport, fisheries, labour and trade, so climate impacts extend beyond crop physiology.

Human Health

Climate change affects health through heat exposure, air quality, wildfire smoke, flood injury, food and water risks, infectious-disease ecology and disruption of health infrastructure.

Risk is unequal because age, occupation, housing, access to cooling, health conditions and local infrastructure influence vulnerability. The same temperature can produce very different outcomes in different communities.

Public-health planning therefore combines climate information with social and medical data rather than treating temperature alone as the whole problem.

Cities

Cities often experience higher temperatures than surrounding rural areas because dark surfaces absorb heat, vegetation is reduced and buildings alter airflow. This urban heat-island effect can compound regional climate warming.

Dense development also concentrates people and infrastructure, increasing exposure to heat, intense rainfall and coastal flooding. At the same time, cities can change building design, drainage, shade, transport and energy systems relatively quickly compared with some larger systems.

Urban climate risk is therefore shaped by both global climate change and local design choices.

Infrastructure and Compound Risk

Climate impacts often arrive as combinations rather than isolated hazards. Heat can increase electricity demand while reducing the efficiency of thermal power plants. Drought can lower reservoir levels at the same time wildfire threatens transmission lines. Heavy rainfall can overwhelm drainage while high tide slows the discharge of floodwater.

Infrastructure planning therefore uses compound-risk analysis: not only how likely each hazard is, but how failures interact across power, transport, water, communications and health systems. Resilience depends on redundancy, maintenance, design standards and the ability to recover when multiple stresses occur together.

Climate Models

Climate models are numerical representations of the atmosphere, ocean, land, ice and their interactions based on physical laws. They divide Earth into three-dimensional grids and calculate how energy, momentum, water and other quantities move through time.

Processes smaller than the grid, such as individual clouds, must be represented through parameterisations. Models are tested against historical climate, seasonal cycles, volcanic events and many other observations.

Models are not crystal balls. They generate conditional projections based on assumptions about future forcing and include uncertainty ranges. Their value comes from physically consistent simulation and comparison across independent models and observations.

Climate Sensitivity

Climate sensitivity describes how much global temperature eventually changes after a sustained change in greenhouse forcing, commonly framed around a doubling of atmospheric carbon dioxide.

The response includes fast feedbacks such as water vapour, clouds and sea ice. Estimates are constrained by climate models, modern observations, historical changes and evidence from past climates.

Uncertainty in sensitivity does not imply uncertainty about whether carbon dioxide warms the planet. It concerns the exact magnitude and timing of the response within a well-established physical mechanism.

Natural Climate Variability

Climate varies naturally through processes such as El Niño and La Niña, volcanic eruptions, ocean cycles and solar changes. These can temporarily speed, slow or redistribute warming.

El Niño, for example, reorganises tropical Pacific ocean-atmosphere circulation and influences global temperature and rainfall patterns. A major volcanic eruption can inject reflective aerosols into the stratosphere and cool global temperatures temporarily.

Scientists account for these influences when estimating long-term human-caused trends. Natural variability explains fluctuations around the trend, not the sustained greenhouse-driven energy imbalance.

How We Know the Recent Warming Is Human-Caused

Attribution relies on multiple fingerprints. Greenhouse-gas concentrations have risen in ways consistent with fossil-fuel and land-use sources. The lower atmosphere and surface have warmed while the stratosphere has cooled, a pattern expected from increased greenhouse gases rather than stronger sunlight alone.

Oceans have accumulated heat, glaciers and ice sheets have lost mass, sea level has risen and seasonal patterns have shifted. Models reproduce the observed long-term warming only when human forcings are included alongside natural factors.

No single measurement carries the conclusion. The strength comes from independent observations matching physical expectations.

Paleoclimate Evidence

Ice cores, marine sediments, tree rings, corals, cave deposits and other proxies preserve evidence of past climates. They show that climate has changed naturally many times because of orbital cycles, volcanic activity, solar variation and greenhouse-gas feedbacks.

Past climate change does not contradict modern human-caused warming. It demonstrates that Earth’s climate responds strongly to changes in energy balance and greenhouse gases.

Paleoclimate records extend understanding beyond the short instrumental era and help test whether models can reproduce very different climate states.

Mitigation

Mitigation means reducing the magnitude of future climate change by limiting greenhouse-gas emissions or increasing durable removals. Approaches include low-carbon electricity, energy efficiency, electrification, methane reduction, industrial changes, land management and carbon removal.

Different approaches have different costs, constraints, land needs, material requirements and timescales. Because carbon dioxide accumulates, long-term temperature stabilisation ultimately requires bringing net carbon dioxide emissions to approximately zero while addressing other greenhouse gases as well.

Mitigation is therefore about changing the future energy balance, not changing yesterday’s weather.

Adaptation

Adaptation means adjusting human and natural systems to reduce harm or take advantage of changed conditions. Examples include heat-health plans, flood protection, drought-tolerant crops, water storage, coastal planning and ecosystem restoration.

Adaptation can substantially reduce risk, but it cannot eliminate every impact. Some systems have physical or financial limits, and adaptation becomes harder as warming increases.

Mitigation and adaptation solve different parts of the problem: mitigation limits the scale of change, while adaptation manages consequences that occur anyway.

Carbon Removal

Carbon dioxide can be removed from the atmosphere through biological processes such as forest growth and soil carbon storage or through engineered methods such as direct air capture and mineralisation.

Removal is not equivalent to avoiding emissions. Many biological stores can be reversed by fire, drought or land-use change, while engineered methods require energy, infrastructure and long-term storage verification.

Carbon removal is most useful when discussed in terms of amount, permanence, additionality, monitoring and opportunity cost rather than as a vague promise to “offset” emissions.

A Worked Example: Why One Extra Tonne of CO₂ Matters

Imagine one tonne of carbon dioxide is emitted from burning fuel. That tonne mixes into the atmosphere rather than forming a local blanket over the source. Natural sinks absorb some of the added carbon over time, but a fraction remains in the atmosphere for very long periods.

The added concentration contributes a tiny amount of radiative forcing. One tonne is individually small, but billions of tonnes accumulate. Climate change is therefore a cumulative-stock problem: many small emissions combine into a large planetary effect.

This helps explain why annual emissions and cumulative emissions are both important metrics.

A Worked Example: Why Sea Level Keeps Responding

Suppose atmospheric greenhouse gases stabilise at a level that holds global temperature above its earlier average. Ocean water already warmed will remain expanded, and deeper ocean layers can continue adjusting. Glaciers and ice sheets may also respond slowly to sustained warmth.

Sea level can therefore keep changing after surface temperature stops rising rapidly. Different parts of the climate system have different response times.

This lag is why climate commitments matter: today’s forcing can shape conditions for decades, centuries or longer depending on the component.

Common Misconceptions About Climate Change

One misconception is that a cold winter disproves global warming. Weather variability continues in a warming climate. Another is that climate has never changed naturally before. It has, but past natural changes do not explain away current human forcing.

A third misconception is that carbon dioxide is too small a fraction of the atmosphere to matter. Radiative impact depends on molecular absorption properties, not simply percentage by volume. Another is that models must predict every storm correctly to be useful; climate models are designed mainly to simulate statistical climate behaviour and physical responses.

Finally, not every climate impact is uniform. Regional differences are expected and scientifically important.

How to Read Climate Claims Critically

Ask whether a claim concerns global climate, a region or one weather event. Check the time period. Distinguish temperature from heat content, emissions from concentration, and short-term variability from long-term trend.

Look for primary measurements or assessments that synthesize many studies. Beware of graphs with cherry-picked start dates, missing units or hidden baselines. A valid climate argument should survive changes in one dataset because the evidence comes from many independent observing systems.

Good climate literacy is less about memorising one number and more about understanding mechanisms, scales and uncertainty.

Frequently Asked Questions

Is global warming the same as climate change?

Global warming refers mainly to rising average global temperature. Climate change includes that warming plus resulting changes in rainfall, oceans, ice, ecosystems, sea level and extremes.

Does carbon dioxide always warm the atmosphere?

Carbon dioxide absorbs and emits infrared radiation. Increasing its concentration changes Earth’s radiative balance in a warming direction under present conditions, with the final response shaped by feedbacks and heat uptake.

Why do scientists use 30-year climate averages?

Long averaging periods help distinguish persistent climate patterns from year-to-year weather variability, though researchers use many timescales depending on the question.

Can planting trees stop climate change by itself?

Forests can store carbon and provide major ecological benefits, but biological storage is limited and reversible. It cannot substitute for reducing all large ongoing fossil carbon emissions.

Will every place get hotter and drier?

No. Global temperature rises overall, but regional temperature and rainfall responses differ. Some regions become wetter, some drier and many experience shifts in seasonal patterns and extremes.

The Big Picture

Climate change is an energy-balance problem expressed through a complex Earth system. Greenhouse gases alter infrared radiation. Oceans store heat. Ice and ecosystems respond. Feedbacks amplify or moderate changes. Weather continues to fluctuate inside the shifting climate background.

The evidence comes from physics, direct observations, paleoclimate records and models that connect causes with consequences. No single heatwave, glacier or graph is the entire case. The case is the consistency of many independent measurements with the same underlying mechanism.

The strongest way to understand climate change is to follow the chain: emissions change atmospheric composition; composition changes radiative balance; energy imbalance warms the system; warming changes oceans, ice, water cycles and ecosystems; those changes alter risks for people and nature.