Global warming is a long-term trend of increasing global average temperature. We still have weather, which causes fluctuations around a rising trend line. Those who live in areas with distinct seasons are well aware of this. A new season brings a much faster change than global warming does. The principle is basically the same. In the spring, a cold front may cool the weather a week or two. But most people realize, however, that summer is coming. The cooling period is just a skip down for a while before we get back to a rising temperature after the trend line.
Average monthly temperatures may vary from one year to the next by 5-6 degrees. This is weather variation. Global average temperature increase has roughly been slightly less than 0,2° C per decade, or less than 0,02° C on average per year over the last decades – for the time being. That is the climate trend. This is why you should not confuse weather with climate. When you want to take a closer look at climate trends, you go to the baseline: the Normal, and compare average weather over at least five years to this baseline. Any period shorter than this is weather variations and not climate. –The Normal is calculated for a period of 30 years.

When measuring the average temperature over decades, there is a clear warming.. Global warming the last three decades has been dramatic. Source: World Meteorological Organisation, 2013
Temperature rise accelerates
For the last 50 years, global temperature rose at an average rate of about 0.13°C (around one-quarter degree Fahrenheit) per decade—around twice as fast as the 0.06°C per decade increase observed over the previous half-century. In the next 20 years, scientists project that global average temperature will rise by around 0.2°C (about one-third of a degree Fahrenheit) per decade (NOAA 2016).

” The average global temperature across land and ocean surface areas for 2015 was 0.90°C (1.62°F) above the 20th century average of 13.9°C (57.0°F), beating the previous record warmth of 2014 by 0.16°C (0.29°F). This is not only the highest calendar year temperature, but also the highest temperature for any 12-month period on record. ”
Hansen, J. and Sato, M. (2020) Accelerated global warming
2015 record hot
2015 has clearly been warmer than 2014, although northern Europe has not had a particularly hot summer. The rest of the world has had an exceptionally warm period.

The 16 warmest years that have been recorded during the period between 1880 -2015, all occurred in this century, except 1998, which tied as the sixth warmest. (National Oceanic and Atmospheric Administration, 2016)
2016 even warmer
BBC (2016) Six graphics that explain climate change
https://www.ncdc.noaa.gov/sotc/global/201713
According to NASA (2016) , “the Earth’s climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives. The current warming trend is of particular significance because most of it is very likely human-induced and proceeding at a rate that is unprecedented in the past 1,300 years.1
GISS Surface Temperature Analysis. Analysis Graphs and Plots 2018
Global Temperature — More Figures (2018)
2021 Tied for 6th Warmest Year in Continued Trend, NASA Analysis Shows (2022)
Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture, collecting many different types of information about our planet and its climate on a global scale. This body of data, collected over many years, reveals the signals of a changing climate”.
Earth’s 2015 surface temperatures were the warmest since modern record keeping began in 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA). Globally-averaged temperatures in 2015 shattered the previous mark set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius). Only once before, in 1998, has the new record been greater than the old record by this much.
This color-coded map displays a progression of changing global surface temperature anomalies from 1880 through 2015. Higher than normal temperatures are shown in red and lower then normal termperatures are shown in blue. The final frame represents the global temperatures 5-year averaged from 2011 through 2015. Scale in degree Celsius.
NASA/Goddard Space Flight Center Scientific Visualization Studio. Data provided by Robert B. Schmunk (NASA/GSFC GISS).
There is a clear scientific consensus: Earth’s climate is warming (NASA 2016)
“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased” (IPCC the physical science 2013).
Each of the last four decades has been successively warmer than any decade that preceded it since 1850. Global surface temperature in the first two decades of the 21st century (2001–2020) was 0.99 [0.84 to 1.10] °C higher than 1850–1900.
Global surface temperature was 1.09 [0.95 to 1.20] °C higher in 2011–2020 than 1850–1900, with larger
increases over land (1.59 [1.34 to 1.83] °C) than over the ocean (0.88 [0.68 to 1.01] °C). The estimated increase in global surface temperature since AR5 is principally due to further warming since 2003–2012 (+0.19 [0.16 to 0.22] °C).
Additionally, methodological advances and new datasets contributed approximately 0.1°C to the updated estimate of warming in AR6. IPCC 2021: Climate Change 2021 The Physical Science Basis
97% of Experts Agree (Huffington Post May 2017)
A scientific fact: The world is getting warmer. And the cause is human activities
- Identifying Fake News: An Infographic and Educator Resources
- Those 3% of scientific papers that deny climate change? A review found them all flawed (Sept 2017).
- How Scientists Cracked the Climate Change Case. The biggest crime scene on the planet is the planet. We know the earth is warming, but who or what is causing it? (NYT 2018)
List of Worldwide Scientific Organizations that Hold the Position That
Climate Change Has Been Caused by Human Action
https://www.opr.ca.gov/s_listoforganizations.php
Consensus on Consensus: 97% of the World’s Climate Scientists Say Humans Are Causing Climate Change
Causes of global warming: How scientists know that humans are responsible
Those 3% of scientific papers that deny climate change? A review found them all flawed (Sept 2017).
Climate change: Is your opinion informed by science? Take our quiz! (Christian Science Monitor)
Climate change explained (UK Gov)
Climate change is happening and is due to human activity, this includes global warming and greater risk of flooding, droughts and heat waves.
https://www.gov.uk/guidance/climate-change-explained
Who is responsible? Names and Locations of the Top 100 People Killing the Planet
“The earth is not dying, it is being killed, and those who are killing it have names and addresses.” – Utah Phillips
Just 100 companies are responsible for more than 70% of the world’s greenhouse gas emissions since 1988. The guys who run those companies – and they are mostly guys – have gotten rich on the backs of literally all life on Earth. Their business model relies on the destruction of the only home humanity has ever known. Meanwhile, we misdirect our outrage at our neighbors, friends, and family for using plastic straws or not recycling. If there is anyone who deserves the outrage of all 7.5 billion of us, it’s these 100 people right here. Combined, they control the majority of the world’s mineral rights – the “right” to exploit the remaining unextracted oil, gas, and coal. They need to know that we won’t leave them alone until they agree to Keep It In The Ground. Not just their companies, but them. Now it’s personal.
https://www.filmsforaction.org/articles/names-and-locations-of-the-top-100-people-killing-the-planet/
Read more
AR6 Climate Change 2021: The Physical Science Basis
- WMO 2022: Climate change puts energy security at risk
- 2021-was-one-of-the-hottest-years-on-record-and-it-could-also-be-the-coldest-well-ever-see-again
- Direct Observations Confirm That Humans Are Throwing Earth’s Energy Budget off Balance
- Joseph Romm: Climate Change What Everyone Needs to know (2022)
- Climate change: IPCC report is ‘code red for humanity’ (BBC 2021)
- AR5 UN – IPCC Synthesis Report
- Direct Observations Confirm That Humans Are Throwing Earth’s Energy Budget off Balance
- NASA Study Finds Direct Proof of Greenhouse Effect
- Planetwide ecocide
- The Guardian: Climate change
- ‘No doubt left’ about scientific consensus on global warming, say experts
Extensive historical data shows recent extreme warming is unprecedented in past 2,000 years (2019) - NYT (2020) 2019 Was Second Hottest Year on Record
- ‘Why have carbon dioxide levels risen and fallen in the past?’
- Romm, J. Climate change
- Earth’s energy imbalance removes almost all doubt from human-made climate change Researchers studying Earth’s absorption of the sun’s energy found a less than 1 percent probability that the recent changes occurred naturally (2021)
. - WMO (2019) Global Climate in 2015-2019: Climate change accelerates
. Observational determination of surface radiative forcing by CO2 from 2000 to 2010
How do we know that recent CO2 increases are due to human activities?
- Why natural cycles only play small role in rate of global warming
. - The Simple Proof of Man-Made Global Warming
- Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature
- Carbon Dioxide Controls Earth’s Temperature
- On the causal structure between CO2 and global temperature
- Studies: atmospheric CO2 drives climate change ancient and modern.
- 99.999% certainty humans are driving global warming: new study
- Fifth Assessment Report – Working Group I
- What’s in a name? Weather, global warming and climate change (NASA)
- Evidence for man-made global warming hits ‘gold standard’: scientists
- What is global warming? (National Geographic)
- The reason why Earth’s climate creates destruction from a 1°C rise in temperature: It’s a mind-boggling amount of energy.
- 2018 – the hottest La Niña year ever recorded
The past five years are the five hottest since the launch of reliable global measurements more than a century ago - Tropospheric Warming Over The Past Two Decades (Nature, May 2017)
- How We Know Humans Are Causing Global Warming
- Massive Government Report Says Climate Is Warming And Humans Are The Cause (Nov 2017)
- U.S. Report Says Humans Cause Climate Change, Contradicting Top Trump Officials (Nov 2017)
- No climate conspiracy: NOAA temperature adjustments bring data closer to pristine
- That Global Warming Hiatus? It Never Happened. Two New Studies Explain Why. (2018)A new study finds that NOAA temperature adjustments are doing exactly what they’re supposed to (Nov 2017)
- Climate change: A guide for the perplexed (New Scientist Aug 2017)
- Possible good news about climate change leads to confused coverage. Did warming projections just get blown up? No. No they did not. (Sept 2017)
- When media sceptics misrepresent our climate research we must speak out (Sept 2017)
- Taking the Pulse of the Planet. How fast is Earth warming? Ocean heat content and sea level rise measurements may provide a more reliable answer than atmospheric measurements (Sept 2017)
- The Most Powerful Evidence Climate Scientists Have of Global Warming. The oceans hold the story of a planet warming as fossil fuels are burned. Here is what scientists have discovered, in four charts (Oct 2017)
- State of the climate 2016 (American Met Soc Aug 2017)
- Leaked draft reveals a devastated America, up to 8 feet of sea level rise, 18°F Arctic warming–unless we embrace Paris climate deal (Aug 2017)
- Climate scientists just debunked deniers’ favorite argument (June 2017)
- 2016: one of the warmest two years on record (Met office Jan 2017)
- Infographic: February 2017 U.S. Record Temperatures (May 2017)
- We Have Less Than 5% Chance of Avoiding ‘Dangerous’ Global WarmingWe Have Less Than 5% Chance of Avoiding ‘Dangerous’ Global Warming (Aug 2017)
- Hot, Dry and Worrisome: 2016 Was a Record-Breaking Year for Climate (Aug 2017)
- IPCC: Climate Change 2013: The Physical Science Basis (Video)
- Science made easy – take the dog for a walk. The difference between climate and weather(Video)
- Is climate change caused by human activity? (Met office)
- National Research Council: Climate change: evidence, impacts and choices (NRC)
- Heat records have become the new normal (Nov 2016)
- Responsible scientists on global warming (Sept 2016)
- Heated debates ignore an overheating planet (Oct 2016)
- An Open Letter Regarding Climate Change From Concerned Members of the U.S. National Academy of Sciences (Sept 2016)
- Royal Society: Are climate changes of a few degrees a cause for concern?
- Recalculating the Climate Math. The numbers on global warming are even scarier than we thought (Sept 2016)
- Ten Clear Indicators Our Climate Is Changing
- Nasa: Earth is warming at a pace ‘unprecedented in 1,000 years’ (Aug 2016)
- Earth ‘Locked Into’ Temperatures Not Seen in 2 Million Years
- Three Ways Climate Deniers Cherry-Pick Facts about Climate Change
- Science museum: Climate Science Info Zone
- Short Answers to Hard Questions About Climate Change
- The Earth is warming up! 2 °C is a limit that we cannot cross
- Climate disruption in overdrive: submerged cities and melting that “feeds on itself”
- Time magazine got global warming right in 2006: “Be worried. Be very worried” (March 2016)
- Bill Nye vs. Sarah Palin on Climate Change: Who Do You Believe? (April 2016)
- Bill Nye: Why I’m Taking Climate Deniers Head On: Carbon dioxide has an enormous effect on planetary temperatures.
- Burning All Fossil Fuels Would Lead to a 17 C Rise in Arctic Temperatures (May 2016)
- How Scientists Know Climate Change Is Happening
- Romm, J. (2016) One Fact About Climate Change That’s Worth Repeating
- Romm, J. (2016) Sorry Deniers, Even Satellites Confirm Record Global Warming. The planet just had its hottest 12 months on record
- The ‘best available science’ to inform 1.5 °C policy choices
- The Earth is warming at scary rates, and this GIF proves it
- Climate Change Cartoons – Must I Draw You A Picture?
- Elon Musk’s Unbelievably Simple 12-minute Killer Break Down on Climate Change
- Climate Inaction Figures: They Distort Facts, Twist Logic and Reject Science
- A world at war: We’re under attack from climate change—and our only hope is to mobilize like we did in WWII.
- Soaring Temperatures Will Make It Too Hot to Work, UN Warns (July 2016) (Bloomberg)
- It’s Official: August Was the 16th Consecutive Record-Breaking Hottest Month (sept 2016)
- Bill Nye Destroys Climate Change Conspiracy Theories
- Who’s Driving Climate Denial? Big Companies and Conservative Media
- Michael Mann’s Hotlist of the 9 Most Prominent Climate Deniers
- Ocean Warming Is ‘Greatest Hidden Challenge of Our Generation’
- Greenland’s receding icecap to expose top-secret US nuclear project
- UNFCCC: UN climate change newsroom
- Here Are All the Climate Records Earth Shattered Last Year (Sept 2016)
- We’re Past the Point of No Return for Climate ChangeEarth is in the danger zone, and every day we burn fossil fuels brings it closer to destruction. (Oct 2016)
- Humanity Has Entered New Climate Reality Era (WMO Oct 2016)
- Uncovered: Fossil Fuel Industry Has Back-Door Access to U.N. Climate Talks
- 7 Key Scenes in Leonardo DiCaprio’s Climate Film ‘Before the Flood’
- Recalculating the Climate Math. The numbers on global warming are even scarier than we thought. (Nov 2016)
- President Obama: Climate Change Is an ‘Immediate Risk to Our National Security’ (Nov 2016)
- Last 5 Years Hottest on Record, Human Footprint ‘Increasingly Visible’ (Nov 2016)
- China minister confirms Beijing is not behind climate ‘hoax’ (Nov 2016)
- Bob Rich: There IS no global warming?
- The Weather Channel to Breitbart: ‘Earth Is Not Cooling, Climate Change Is Real’ (Dec 2016)
- World on track for 3C of warming under current global climate pledges, warns UN (Dec 2016)
- It Was Hot in 2016 And It Will Be Almost As Hot Again Next Year (Dec 2016)
- NOAA challenged the global warming ‘pause.’ Now new research says the agency was right (Jan 2017)
- Already Debunked Global Warming ‘Hiatus’ Gets Another Dunking (Jan 2017)
- Norge fra 1900 til i dag -Vær og klima i Norge har variert stort i gjennom historien
- NOAA: Study: Global Warming Hiatus Attributed to Redistribution
- Two Top TV Mets Address Climate Change A challenge and a response on TV weathercasters’ ‘responsibility’ to address climate change science … and background to help them do so (Jan 2017)
- Identifying Fake News: An Infographic and Educator Resources
- The First Climate Model Turns 50, And Predicted Global Warming Almost Perfectly (March 2017)
- Facts And Evidence Matter In Confronting Climate Crisis
- Fakery 2: More Funny Finances, Free Of Tax
- GISS Surface Temperature Analysis (GISTEMP) Frequently Asked Questions (FAQ)
- We aren’t doomed by climate change. Right now we are choosing to be doomed
- Scientists Solve Climate Hiatus ‘Puzzle of the Century’: So Now What? (July 2017)
- We Looked at 1,154 Climate Science Results and Found No Evidence of ‘Publication Bias’
- A wet, hot future
Next
Home | Chapter 1 | 1. The natural Greenhouse effect |
Chapter 2 | 2. Global Warming | |
2.1 Authoritative sources | ||
2.2 The Sun? | ||
2.3 Volcanoes? | ||
2.4 Winter is cold? | ||
2.5 Mitigation and adaptation | ||
Chapter 3 | 3. Impacts |