Welcome to the October edition of Stanford University’s Understand Energy Learning Hub Energy Spotlight. This month, we are covering energy and climate change. If you like what you see, please share widely and encourage others to subscribe. You can also check out all of our past issues!
What you need to know
Significance: Energy use is the leading cause of climate change, primarily from the burning of fossil fuels (coal, oil, and natural gas). Climate change is an urgent problem for maintaining a livable planet for humans. We are already seeing the impacts of climate change, including unprecedented droughts, heat waves, wildfires, floods, severe weather events, and species extinctions. For example, in 2024, more than 600 extreme weather events across the globe displaced 824,000 people, injured 1.1 million, and killed 1,700.
The good news: We have scalable and cost-effective tools and solutions at our fingertips today to address climate change and allow us to live in a healthier environment and climate.
What is climate change? Climate change refers to long-term shifts in the Earth’s temperature and weather patterns. Present day climate change is a result of carbon-intensive human activities like fossil fuel combustion, land use changes, and agriculture. These activities result in higher concentrations of greenhouse gases (GHGs) like carbon dioxide (CO₂) and methane (CH₄) in our atmosphere. We have a limited global carbon budget (i.e., the maximum amount of CO₂ and other GHGs we can emit into the atmosphere) before we exceed key climate tipping points.
Major impacts of climate change include:
- Sea level rise: Global warming causes sea level rise in two ways: 1) Ocean water expands as it warms; and 2) Higher temperatures cause land-based glaciers and ice sheets to melt, adding more water to our oceans. Over the past 100 years, our global mean sea level has increased by 6-10 inches, and the rate of sea level rise is increasing. The Global Tipping Points 2025 report predicts we've already locked in long-term multi-meter sea level rise with the high risk of collapse of Greenland and West Antarctic ice sheets.
- Wildfires: Climate change increases the frequency and intensity of wildfires because it creates hotter and drier conditions. For example, in Canada, the average area burned during a wildfire has doubled since 1970. The total area burned in the 2023 Canadian wildfire season, 45.5 million acres, was six times the 10-year average. Wildfires also exacerbate global warming by releasing CO₂ into the atmosphere and by destroying forests, an important natural carbon sink.
- Extinctions: Climate change increases species extinctions by causing temperatures that exceed their physiological tolerance, altering habitats faster than they can adapt or migrate, and disrupting food webs. About one-third of all plant and animal species are predicted to be at high risk of extinction by 2070 if climate change continues at its current rate.
- Coral bleaching: Warmer ocean temperatures stress the corals, causing them to expel the symbiotic algae living in their tissues and turn completely white. Bleached corals are more vulnerable to morbidity and mortality. Warm-water coral reefs have experienced the worst bleaching event on record during 2023-2025.
Read more about climate change impacts in our Climate Change Fast Facts.
Solving climate change
Climate change is a global challenge affecting everyone on Earth. To solve climate change, we need three things:
- Science (we have this)
- Social will (we need more of this)
- Solutions (we have these but need to implement them more quickly)
1. Science
The greenhouse effect is a naturally occurring phenomenon that regulates Earth’s temperature and makes life on Earth possible. Sunlight hits the Earth, the Earth warms, and the Earth emits infrared radiation (heat). GHGs absorb some of the infrared radiation that would otherwise be released to space, further warming the Earth to a temperature that can support life. Naturally occurring GHGs like CO₂ and water vapor are part of the natural carbon cycle.
Global warming: Rising GHG levels due to carbon-intensive human activities since pre-industrial times have thrown the natural carbon cycle out of balance. Increasing concentrations of GHGs in Earth’s atmosphere are causing an increase in the Earth’s surface temperature, which is known as global warming. Though people tend to use the terms global warming and climate change interchangeably, global warming is just one aspect of climate change. Climate change includes global warming and other climate effects like melting glaciers, more frequent droughts, and increased severe weather events.
The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. Their chart below shows the spike in global surface temperature due to rising concentrations of GHGs in the Earth's atmosphere.
You've probably heard about the 1.5°C climate target, but 1.5°C is not the point at which we start seeing impacts from climate change. Millions of people are already experiencing impacts of climate change in the form of extreme temperatures, heavy rains, flooding, and more. The 2015 Paris Agreement chose 1.5°C as the global climate target because "both models and paleoclimate data show that beyond 1.5°C, the risk of severe impacts to some ecosystems and locations—including places where people are least responsible for the problem—become larger than the world as a whole was willing to accept."
We are already at 1.3°C. Even if we stopped emitting GHGs today, Earth’s temperature would continue to rise due to a delay between GHG emissions and temperature increase. Every little bit of extra warming will cause increasingly severe impacts.
Anthropogenic GHG emissions: Energy use accounts for over 75% of anthropogenic (human-caused) GHG emissions, mainly from burning fossil fuels. When you burn fossil fuels, you produce CO₂. Other anthropogenic GHG emissions include methane, nitrous oxide (N₂O) and fluorinated gases. We can compare the contributions of different GHGs to global warming using their atmospheric concentrations and global warming potentials (GWP), a measurement of a GHG’s heat-trapping ability relative to CO₂ over specific time intervals. CO₂ is by far the biggest contributor, accounting for 74% of anthropogenic GHG emissions in 2022. Methane, 80 times more potent than CO₂ over a 20-year period, accounted for 17%.
Natural carbon sinks: Not all GHG emissions stay in the atmosphere. The Earth has natural sinks that remove CO₂ from the atmosphere and sequester or store it in another form. Natural carbon sinks include the ocean and other large bodies of water, plants, and soil. About 40% of anthropogenic greenhouse gas emissions today are absorbed by natural sinks, but that’s not necessarily a good thing. For example, the ocean is becoming more acidic due to increased CO₂ absorption, making it harder for marine organisms like coral and shellfish to build and maintain their shells and skeletons. And, of course, the GHGs remaining in the atmosphere are contributing to climate change.
Climate feedback loops are self-reinforcing processes that can be positive or negative. Positive feedback loops exacerbate global warming, while negative feedback loops have a cooling effect on the atmosphere. Melting permafrost is an example of a positive feedback loop. Warmer temperatures at the northern latitudes melt frozen ground, releasing methane that has been trapped in the soil and leading to more warming.
2. Social will
The science is clear.
“It is unequivocal that human influence has warmed the atmosphere, ocean and land.”
—Intergovernmental Panel on Climate Change (IPCC), 2023
Now we need the social will to implement and execute policies to limit the worst impacts of climate change. Current policies and commitments are not enough to limit global warming to 1.5°C, leaving an “ambition gap.” The world is currently on track for up to 3.1°C of warming in this century based on national policies.
Global GHG emissions pathways
Assigning responsibility for climate change is complicated and controversial yet necessary for setting equitable and effective policies. China is by far the largest GHG emitter today, responsible for over 30% of emissions in 2023. However, the U.S. dominates cumulative GHG emissions since pre-industrial times, accounting for almost 25%. Of the major GHG emitters, Australia, the U.S., and Canada lead on a per capita basis.
The impacts of climate change are not equitably distributed across the globe. The richest half of the world’s population is responsible for the vast majority of GHG emissions, yet climate change’s most severe impacts disproportionately affect low-income countries and marginalized communities who are less equipped to cope. For example, African nations have produced only a tiny share of the world’s GHG emissions but suffer some of the biggest effects of climate change including increasing droughts, flooding, and food shortages.
Annual carbon emissions by region, 1750-2023
How we communicate about climate change is important for changing societal mindsets and practices and motivating people and countries to act.
3. Solutions
We have tools and solutions to tackle climate change, stabilize GHGs at safe levels, and reduce energy costs, including:
- Energy efficiency (Heat pumps, which are 3-4 times more efficient, outsold gas furnaces in the U.S. in 2022 and 2023.)
- Electrification (Electric vehicles are projected to make up over 40% of total car sales by 2030.)
- Decarbonization of electricity generation (Wind and solar are the cheapest and fastest-growing energy resources worldwide.)
- Carbon management (Advance market commitments and self-imposed carbon reduction goals for businesses are driving growth in durable carbon dioxide removal purchases.)
Clean energy transitions are happening, but can we make them happen fast enough?
World electricity generation in the Stated Policies Scenario, 2010-2035
Every job is a climate job. You can make choices personally and professionally to help mitigate climate change. Let’s take action and build the future we want!
In the news
News: The world has reached its first climate tipping point with the widespread mortality of warm-water coral reefs on which nearly a billion people and a quarter of all marine life depend. This die-off is almost irreversible unless global surface temperature quickly returns to 1.0°C above pre-industrial levels. We are also on the brink of reaching more tipping points, including:
- Widespread dieback of the Amazon rainforest on which over 100 million people depend
- Irreversible melting of ice sheets from Greenland to West Antarctica, leading to long-term multi-meter sea level rise
- Collapse of the Atlantic Meridional Overturning Circulation, an ocean current that helps ensure mild winters in northern Europe and is important for global food security
Risks of Earth system tipping points increase with global warming
Context: We are reaching key climate tipping points at lower global surface temperatures than expected. These tipping points will have catastrophic and likely irreversible effects on humans and ecosystems. Current climate policies don’t typically focus on tipping points and allow for an overshoot of the global surface warming target, assuming that warming impacts can be reversed. “Preventing tipping points requires ‘frontloaded’ mitigation pathways that minimize peak global temperature, the duration of the overshoot period above 1.5°C, and the return time below 1.5°C,” according to Dr. Manjana Milkoreit, from the University of Oslo and contributor to the Global Tipping Points 2025 report.
Fun Fact
Desert lions in Namibia are adapting to climate change by becoming the world’s only maritime lions.
Twelve desert lions have moved from the arid Namib Desert to the Atlantic Ocean. In 2015, the lions started hunting coastal prey like cormorants, flamingos, and seals on the beach, after a climate change-driven drought decimated their usual inland prey of ostriches, oryxes and springboks. The lions have drastically changed their diet and behavior to adapt to the new habitat and appear to be thriving. Read more about the maritime lions.
Want to test your knowledge of climate change?
Take our quiz
Understand Energy team contributors: Dr. Diana Gragg, Kirsten Stasio, Racheal Moore, Sharon Poore, and Shirley Chang
The data in this issue are current as of October 2025. For the most current data, visit our Climate Change Fast Facts.
