||"It's the sun"
In the last 35 years of global warming, sun and climate have been going in opposite directions
In the last 35 years of global warming, the sun has shown a slight cooling trend. Sun and climate have been going in opposite directions.
||"There is no consensus"
||97% of climate experts agree humans are causing global warming.
||That humans are causing global warming is the position of the Academies of Science from 19 countries plus many scientific organizations that study climate science. More specifically, around 95% of active climate researchers actively publishing climate papers endorse the consensus position.
||"Models are unreliable"
||Models successfully reproduce temperatures since 1900 globally, by land, in the air and the ocean.
||While there are uncertainties with climate models, they successfully reproduce the past and have made predictions that have been subsequently confirmed by observations.
||"Animals and plants can adapt"
||Global warming will cause mass extinctions of species that cannot adapt on short time scales.
||A large number of ancient mass extinction events have been strongly linked to global climate change. Because current climate change is so rapid, the way species typically adapt (eg - migration) is, in most cases, simply not be possible. Global change is simply too pervasive and occurring too rapidly.
||"Antarctica is gaining ice"
||Satellites measure Antarctica losing land ice at an accelerating rate.
||While the interior of East Antarctica is gaining land ice, overall Antarctica is losing land ice at an accelerating rate. Antarctic sea ice is growing despite a strongly warming Southern Ocean.
||"CO2 lags temperature"
||CO2 didn't initiate warming from past ice ages but it did amplify the warming.
||When the Earth comes out of an ice age, the warming is not initiated by CO2 but by changes in the Earth's orbit. The warming causes the oceans to give up CO2. The CO2 amplifies the warming and mixes through the atmosphere, spreading warming throughout the planet. So CO2 causes warming AND rising temperature causes CO2 rise.
||"We're heading into an ice age"
||Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years.
||The warming effect from more CO2 greatly outstrips the influence from changes in the Earth's orbit or solar activity, even if solar levels were to drop to Maunder Minimum levels.
||"Hockey stick is broken"
||Recent studies agree that recent global temperatures are unprecedented in the last 1000 years.
||Since the hockey stick paper in 1998, there have been a number of proxy studies analysing a variety of different sources including corals, stalagmites, tree rings, boreholes and ice cores. They all confirm the original hockey stick conclusion: the 20th century is the warmest in the last 1000 years and that warming was most dramatic after 1920.
||"Hurricanes aren't linked to global warming"
||There is increasing evidence that hurricanes are getting stronger due to global warming.
||It is unclear whether global warming is increasing hurricane frequency but there is increasing evidence that warming increases hurricane intensity.
||"Glaciers are growing"
||Most glaciers are retreating, posing a serious problem for millions who rely on glaciers for water.
||While there are isolated cases of growing glaciers, the overwhelming trend in glaciers worldwide is retreat. In fact, the global melt rate has been accelerating since the mid-1970s.
||"1934 - hottest year on record"
||1934 was one of the hottest years in the US, not globally.
||1934 is the hottest year on record in the USA which only comprises 2% of the globe. According to NASA temperature records, the hottest year on record globally is 2005.
||"Sea level rise is exaggerated"
||A variety of different measurements find steadily rising sea levels over the past century.
||Sea levels are measured by a variety of methods that show close agreement - sediment cores, tidal gauges, satellite measurements. What they find is sea level rise has been steadily accelerating over the past century.
||"Medieval Warm Period was warmer"
||Globally averaged temperature now is higher than global temperature in medieval times.
||While the Medieval Warm Period saw unusually warm temperatures in some regions, globally the planet was cooler than current conditions.
||"Arctic icemelt is a natural cycle"
||Thick arctic sea ice is undergoing a rapid retreat.
||Arctic sea ice has been retreating over the past 30 years. The rate of retreat is accelerating and in fact is exceeding most models' forecasts.
||"Oceans are cooling"
||The most recent ocean measurements show consistent warming.
||Early estimates of ocean heat from the Argo showed a cooling bias due to pressure sensor issues. Recent estimates of ocean heat that take this bias into account show continued warming of the upper ocean. This is confirmed by independent estimates of ocean heat as well as more comprehensive measurements of ocean heat down to 2000 metres deep.
||"IPCC is alarmist"
Numerous papers have documented how IPCC predictions are more likely to underestimate the climate response.
The IPCC lead authors are experts in their field, instructed to fairly represent the full range of the up-to-date, peer-reviewed literature. Consequently, the IPCC reports tend to be cautious in their conclusions. Comparisons to the most recent data consistently finds that climate change is occurring more rapidly and intensely than indicated by IPCC predictions.
||"Polar bear numbers are increasing"
||Polar bears are in danger of extinction as well as many other species.
||While there is some uncertainty on current polar bear population trends, one thing is certain. No sea ice means no seals which means no polar bears. With Arctic sea ice retreating at an accelerating rate, the polar bear is at grave risk of extinction
||"It's not happening"
There are many lines of evidence indicating global warming is unequivocal.
There are many lines of independent empirical evidence for global warming, from accelerated ice loss from the Arctic to Antarctica to the poleward migration of plant and animal species across the globe.
||"Greenland is gaining ice"
||Greenland on the whole is losing ice, as confirmed by satellite measurement.
||While the Greenland interior is in mass balance, the coastlines are losing ice. Overall Greenland is losing ice mass at an accelerating rate. From 2002 to 2009, the rate of ice mass loss doubled.
||"CO2 is plant food"
The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors
The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors
||"Arctic sea ice has recovered"
||Thick arctic sea ice is in rapid retreat.
||Arctic sea ice has been steadily thinning, even in the last few years while the surface ice (eg - sea ice extent) increased slightly. Consequently, the total amount of Arctic sea ice in 2008 and 2009 are the lowest on record.
||"We're coming out of the Little Ice Age"
Scientists have determined that the factors which caused the Little Ice Age cooling are not currently causing global warming
The main driver of the warming from the Little Ice Age to 1940 was the warming sun with a small contribution from volcanic activity. However, solar activity leveled off after 1940 and the net influence from sun and volcano since 1940 has been slight cooling. Greenhouse gases have been the main contributor of warming since 1970.
||"It cooled mid-century"
||Mid-century cooling involved aerosols and is irrelevant for recent global warming.
||There are a number of forcings which affect climate (eg - stratospheric aerosols, solar variations). When all forcings are combined, they show good correlation to global temperature throughout the 20th century including the mid-century cooling period. However, for the last 35 years, the dominant forcing has been CO2.
||"It warmed before 1940 when CO2 was low"
||Early 20th century warming is due to several causes, including rising CO2.
||Early 20th century warming was in large part due to rising solar activity and relatively quiet volcanic activity. However, both factors have played little to no part in the warming since 1975. Solar activity has been steady since the 50's. Volcanoes have been relatively frequent and if anything, have exerted a cooling effect.
||"Satellites show no warming in the troposphere"
||The most recent satellite data show that the earth as a whole is warming.
||Satellite measurements match model results apart from in the tropics. There is uncertainty with the tropical data due to how various teams correct for satellite drift. The U.S. Climate Change Science Program concludes the discrepancy is most likely due to data errors.
||"It's El Niño"
||El Nino has no trend and so is not responsible for the trend of global warming.
||The El Nino Southern Oscillation shows close correlation to global temperatures over the short term. However, it is unable to explain the long term warming trend over the past few decades.
||"It's a natural cycle"
||No known natural forcing fits the fingerprints of observed warming except anthropogenic greenhouse gases.
||A natural cycle requires a forcing, and no known forcing exists that fits the fingerprints of observed warming - except anthropogenic greenhouse gases.
||"There's no tropospheric hot spot"
||We see a clear "short-term hot spot" - there's various evidence for a "long-term hot spot".
||Satellite measurements match model results apart from in the tropics. There is uncertainty with the tropic data due to how various teams correct for satellite drift. The U.S. Climate Change Science Program conclude the discrepancy is most likely due to data errors.
||"It's Pacific Decadal Oscillation"
||The PDO shows no trend, and therefore the PDO is not responsible for the trend of global warming.
||PDO as an oscillation between positive and negative values shows no long term trend, while temperature shows a long term warming trend. When the PDO last switched to a cool phase, global temperatures were about 0.4C cooler than currently. The long term warming trend indicates the total energy in the Earth's climate system is increasing due to an energy imbalance.
||"Scientists can't even predict weather"
||Weather and climate are different; climate predictions do not need weather detail.
||Weather is chaotic, making prediction difficult. However, climate takes a long term view, averaging weather out over time. This removes the chaotic element, enabling climate models to successfully predict future climate change.
||"2nd law of thermodynamics contradicts greenhouse theory"
||The 2nd law of thermodynamics is consistent with the greenhouse effect which is directly observed.
||The atmosphere of the Earth is less able to absorb shortwave radiation from the Sun than thermal radiation coming from the surface. The effect of this disparity is that thermal radiation escaping to space comes mostly from the cold upper atmosphere, while the surface is maintained at a substantially warmer temperature. This is called the "atmospheric greenhouse effect", and without it the Earth's surface would be much colder.
||"Clouds provide negative feedback"
||Evidence is building that net cloud feedback is likely positive and unlikely to be strongly negative.
||Although the cloud feedback is one of the largest remaining uncertainties in climate science, evidence is building that the net cloud feedback is likely positive, and unlikely to be strongly negative.
||"It's the ocean"
||The oceans are warming and moreover are becoming more acidic, threatening the food chain.
||Oceans are warming across the globe. In fact, globally oceans are accumulating energy at a rate of 4 x 1021 Joules per year - equivalent to 127,000 nuclear plants (which have an average output of 1 gigawatt) pouring their energy directly into the world's oceans. This tells us the planet is in energy imbalance - more energy is coming in than radiating back out to space.
||"Corals are resilient to bleaching"
||Globally about 1% of coral is dying out each year.
||On a world scale coral reefs are in decline. Over the last 30-40 years 80% of coral in the Caribbean have been destroyed and 50% in Indonesia and the Pacific. Bleaching associated with the 1982 -1983 El-Nino killed over 95% of coral in the Galapagos Islands and the 1997-1998 El-Nino alone wiped out 16% of all coral on the planet. Globally about 1% of coral is dying out each year.
||"CO2 effect is saturated"
||Direct measurements find that rising CO2 is trapping more heat.
||If the CO2 effect was saturated, adding more CO2 should add no additional greenhouse effect. However, satellite and surface measurements observe an enhanced greenhouse effect at the wavelengths that CO2 absorb energy. This is empirical proof that the CO2 effect is not saturated.
||Methane plays a minor role in global warming but could get much worse if permafrost starts to melt.
||While methane is a more potent greenhouse gas than CO2, there is over 200 times more CO2 in the atmosphere. Hence the amount of warming methane contributes is 28% of the warming CO2 contributes.
||"CO2 measurements are suspect"
||CO2 levels are measured by hundreds of stations across the globe, all reporting the same trend.
||CO2 levels are measured by hundreds of stations scattered across 66 countries which all report the same rising trend.
||"500 scientists refute the consensus"
||Around 97% of climate experts agree that humans are causing global warming.
||Close inspection of the studies alleged to refute man-made global warming finds that many of these papers do no such thing. Of the few studies that do claim to refute man-made global warming, these repeat well debunked myths.
||"Springs aren't advancing"
||Hundreds of flowers across the UK are flowering earlier now than any time in 250 years.
||A synthesis of nearly 400,000 first flowering records covering 405 species across the UK found that British plants are flowering earlier now than at any time in the last 250 years.
||"It's land use"
||Land use plays a minor role in climate change, although carbon sequestration may help to mitigate.
||Correlations between warming and economic activity are most likely spurious. They don't take into account local forcing agents such as tropospheric ozone or black carbon. Correlations are likely over-estimated since grid boxes in both economic and climate data are not independent. Lastly, there is significant independent evidence for warming in the oceans, snow cover and sea ice extent changes.
||"CO2 is not increasing"
||CO2 is increasing rapidly, and is reaching levels not seen on the earth for millions of years.
||Currently, humans are emitting around 29 billion tonnes of carbon dioxide into the atmosphere per year. Around 43% remains in the atmosphere - this is called the 'airborne fraction'. The rest is absorbed by vegetation and the oceans. While there are questions over how much the airborne fraction is increasing, it is clear that the total amount of CO2 in the atmosphere is increasing dramatically. Current CO2 levels are the highest in 15 million years.
||"They changed the name from 'global warming' to 'climate change'"
'Global warming' and 'climate change' mean different things and have both been used for decades.
There have long been claims that some unspecificed "they" has "changed the name from 'global warming' to 'climate change'". In reality, the two terms mean different things, have both been used for decades, and the only individual to have specifically advocated changing the name in this fashion is a global warming 'skeptic'.
||"CO2 is coming from the ocean"
||The ocean is absorbing massive amounts of CO2, and is becoming more acidic as a result.
||Measurements of carbon isotopes and falling oxygen in the atmosphere show that rising carbon dioxide is due to the burning of fossil fuels and cannot be coming from the ocean.
||"CO2 is not the only driver of climate"
||Theory, models and direct measurement confirm CO2 is currently the main driver of climate change.
||While there are many drivers of climate, CO2 is the most dominant radiative forcing and is increasing faster than any other forcing.
||"Southern sea ice is increasing"
||Antarctic sea ice has grown in recent decades despite the Southern Ocean warming at the same time.
||Antarctic sea ice has growing over the last few decades but it certainly is not due to cooling - the Southern Ocean has shown warming over same period. Increasing southern sea ice is due to a combination of complex phenomena including cyclonic winds around Antarctica and changes in ocean circulation.
||"Phil Jones says no global warming since 1995"
||Phil Jones was misquoted.
||When you read Phil Jones' actual words, you see he's saying there is a warming trend but it's not statistically significant. He's not talking about whether warming is actually happening. He's discussing our ability to detect that warming trend in a noisy signal over a short period.
||"Lindzen and Choi find low climate sensitivity"
||Lindzen and Choi’s paper is viewed as unacceptably flawed by other climate scientists.
||Lindzen's analysis has several flaws, such as only looking at data in the tropics. A number of independent studies using near-global satellite data find positive feedback and high climate sensitivity.
||"It's too hard"
||Scientific studies have determined that current technology is sufficient to reduce greenhouse gas emissions enough to avoid dangerous climate change.
||The argument that solving the global warming problem by reducing human greenhouse gas emissions is "too hard" generally stems from the belief that (i) our technology is not sufficiently advanced to achieve significant emissions reductions, and/or (ii) that doing so would cripple the global economy. However, studies have determined that current technology is sufficient to reduce greenhouse gas emissions the necessary amount, and that we can do so without significant impact on the economy.
||"Tree-rings diverge from temperature after 1960"
||This is a detail that is complex, local, and irrelevant to the observed global warming trend.
||The divergence problem is a physical phenomenon - tree growth has slowed or declined in the last few decades, mostly in high northern latitudes. The divergence problem is unprecedented, unique to the last few decades, indicating its cause may be anthropogenic. The cause is likely to be a combination of local and global factors such as warming-induced drought and global dimming. Tree-ring proxy reconstructions are reliable before 1960, tracking closely with the instrumental record and other independent proxies.
||"Roy Spencer finds negative feedback"
||Spencer's model is too simple, excluding important factors like ocean dynamics and treats cloud feedbacks as forcings.
||Spencer and Braswell's study uses an overly simplistic climate model, their conclusions rely on using one particular data set, and their paper does not provide enough information to duplicate the study. The paper is fundamentally flawed and has no scientific merit.
||"Arctic sea ice loss is matched by Antarctic sea ice gain"
||Arctic sea ice loss is three times greater than Antarctic sea ice gain.
||The Arctic trend is in fact more than three times faster than the Antarctic one. The net result is a statistically significant global decrease of more than a million km2.
||"Earth hasn't warmed as much as expected"
||This argument ignores the cooling effect of aerosols and the planet's thermal inertia.
||The argument that "Earth hasn't warmed as much as expected" generally relies on ignoring the factors which have a cooling effect on the Earth's temperatures, and the planet's thermal inertia, which delays the full amount of global warming. When we do the calculations and include all radiative forcings and the amount of heat being absorbed by the oceans, it shows that the Earth has warmed almost exactly as much as we would expect.
||"Less than half of published scientists endorse global warming"
||Around 97% of climate experts agree that humans are causing global warming.
||Schulte's paper makes much of the fact that 48% of the papers they surveyed are neutral papers, refusing to either accept or reject anthropogenic global warming. The fact that so many studies on climate change don't bother to endorse the consensus position is significant because scientists have largely moved from what's causing global warming onto discussing details of the problem (eg - how fast, how soon, impacts, etc).
||"Over 31,000 scientists signed the OISM Petition Project"
||The 'OISM petition' was signed by only a few climatologists.
||The 30,000 scientists and science graduates listed on the OISM petition represent a tiny fraction (0.3%) of all science graduates. More importantly, the OISM list only contains 39 scientists who specialise in climate science.
||Ozone has only a small effect.
||Multiple satellite measurements and ground-based observations have determined the ozone layer has stopped declining since 1995 while temperature trends continue upwards.
||"The IPCC consensus is phoney"
113 nations signed onto the 2007 IPCC report, which is simply a summary of the current body of climate science evidence
Ironically, it's those who are mispresenting Hulme's paper that are the ones being misleading.
||"A drop in volcanic activity caused warming"
||Volcanoes have had no warming effect in recent global warming - if anything, a cooling effect.
||A drop of volcanic activity in the early 20th century may have had a warming effect. However, volcanoes have had no warming effect in the last 40 years of global warming. If anything, they've imposed a slight cooling effect.
||"Trenberth can't account for the lack of warming"
||Trenberth is talking about the details of energy flow, not whether global warming is happening.
||Trenberth's views are clarified in the paper "An imperative for climate change planning: tracking Earth's global energy". We know the planet is continually heating due to increasing carbon dioxide but that surface temperature sometimes have short term cooling periods. This is due to internal variability and Trenberth was lamenting that our observation systems can't comprehensively track all the energy flow through the climate system.
||"CRU tampered with temperature data"
||An independent inquiry went back to primary data sources and were able to replicate CRU's results.
||The Independent Climate Change Email Review went back to primary data sources and were able to replicate CRU's results. This means not only was CRU not hiding anything, but it had nothing to hide. Though CRU neglected to provide an exact list of temperature stations, it could not have hid or tampered with data.
||"Melting ice isn't warming the Arctic"
||Melting ice leads to more sunlight being absorbed by water, thus heating the Arctic.
||Decline in sea ice is the major driver of Arctic amplification. This is evidence by the pattern of atmospheric warming over the Arctic. Maximum warming occurs over the surface during winter while less surface warming is found in summer when heat is being used to melt sea ice. This pattern is consistent with sea ice amplification.
||"Satellite error inflated Great Lakes temperatures"
||Temperature errors in the Great Lakes region are not used in any global temperature records.
||Temperature errors in the Great Lakes region are not incorporated in any of the global mean temperature records. In particular, there is no connection to the satellite microwave temperature analyses by RSS and UAH, which use entirely different sensors operating in a quite different portion of the electromagnetic spectrum.
||"We're heading into cooling"
||There is no scientific basis for claims that the planet will begin to cool in the near future.
||Claims have recently surfaced in the blogosphere that an increasing number of scientists are warning of an imminent global cooling, some even going so far as to call it a "growing consensus". There are two major flaws in these blog articles, (i) there is no scientific basis for claims that the planet will begin to cool in the near future, and (ii) many of the listed scientists are not predicting global cooling.
||"Most of the last 10,000 years were warmer"
||This argument uses regional temperature data that ends in 1855, long before modern global warming began.
||This argument uses temperatures from the top of the Greenland ice sheet. This data ends in 1855, long before modern global warming began. It also reflects regional Greenland warming, not global warming.
||"The sun is getting hotter"
||The sun has just had the deepest solar minimum in 100 years.
||Various independent measurements of solar activity all confirm the sun has shown a slight cooling trend since 1978.
||"Water vapor in the stratosphere stopped global warming"
||This possibility just means that future global warming could be even worse.
||The effect from stratospheric water vapor contributes a fraction of the temperature change imposed from man-made greenhouse gases. Also, it's not yet clear whether changes in stratospheric water vapor are caused by a climate feedback or internal variability (eg - linked to El Nino Southern Oscillation). However, the long term warming trend seems to speak against the possibility of a negative feedback.
||"An exponential increase in CO2 will result in a linear increase in temperature"
||CO2 levels are rising so fast that unless we decrease emissions, global warming will accelerate this century.
||Despite the logarithmic relationship between CO2 and surface temperatures, atmospheric CO2 levels are rising so fast that unless we dramatically decrease our emissions, global warming will accelerate over the 21st Century.
||"Mauna Loa is a volcano"
||The global trend is calculated from hundreds of CO2 measuring stations and confirmed by satellites.
||The trend in CO2 at Mauna Loa is practically identical to the global trend because CO2 mixes well throughout the atmosphere. The global trend is calculated from hundreds of CO2 measuring stations and is consistent with independently measurements from satellites.
||"Antarctica is too cold to lose ice"
||Glaciers are sliding faster into the ocean because ice shelves are thinning due to warming oceans.
||Antarctica is losing ice because its glaciers are speeding up. This is due to melt water lubricating the base of the glaciers and the removal of ice shelves which act as a "speed bump" slowing the glacier flow. The ice shelves are thinning due to warming ocean waters.
||"Skeptics were kept out of the IPCC?"
Official records, Editors and emails suggest CRU scientists acted in the spirit if not the letter of IPCC rules.
The Independent Climate Change Email Review investigated the CRU scientists' actions as IPCC authors. Official records, Review Editors, and even the emails themselves suggest the CRU scientists acted in the spirit if not the letter of the IPCC rules. Anyway, the relevant texts were team responsibilities.
||"CO2 was higher in the late Ordovician"
||The sun was much cooler during the Ordovician.
||During the Ordovician, solar output was much lower than current levels. Consequently, CO2 levels only needed to fall below 3000 parts per million for glaciation to be possible. The latest CO2 data calculated from sediment cores show that CO2 levels fell sharply during the late Ordovician due to high rock weathering removing CO2 from the air. Thus the CO2 record during the late Ordovician is entirely consistent with the notion that CO2 is a strong driver of climate.
||"Scientists retracted claim that sea levels are rising"
||The Siddall 2009 paper was retracted because its predicted sea level rise was too low.
||The retracted paper actually predicts a low range of future sea level rise. The retraction removes a lower bound of sea level prediction. This increases confidence in other peer-reviewed research predicting sea level rise of 80cm to 2 metres by 2100.
||"Greenland has only lost a tiny fraction of its ice mass"
||Greenland's ice loss is accelerating & will add metres of sea level rise in upcoming centuries.
||Multiple lines of evidence indicate Greenland's ice loss is accelerating and will contribute sea level rise in the order of metres over the next few centuries.
||"Royal Society embraces skepticism"
||The Royal Society still strongly state that human activity is the dominant cause of global warming.
||The Royal Society states that "There is strong evidence that changes in greenhouse gas concentrations due to human activity are the dominant cause of the global warming that has taken place over the last half century" and "The decade 2000-2009 was, globally, around 0.15 °C warmer than the decade 1990-1999". They are not denying anthropogenic global warming.
||"It's satellite microwave transmissions"
||Satellite transmissions are extremely small and irrelevant.
||A generous estimate of the energy generated by satellites is around 1 million times too small to cause global warming.
||"Sea level fell in 2010"
||The temporary drop in sea level in 2010 was due to intense land flooding caused by a strong La Nina.
||Temporary sea level fluctuations are the result of large exchanges of water between land and ocean in the form of rain and snow. This averages out to zero over time, so it does not affect long-term sea level rise from the addition of melting land ice, and thermal expansion from warming oceans.
||"We didn't have global warming during the Industrial Revolution"
||CO2 emissions were much smaller 100 years ago.
||Global CO2 emissions during the Industrial Revolution were a fraction of the CO2 we are currently emitting now.
||"Postma disproved the greenhouse effect"
||Postma's model contains many simple errors; in no way does Postma undermine the existence or necessity of the greenhouse effect.
||Joseph Postma published an article criticizing a very simple model that nonetheless produces useful results. He made several very simple errors along the way, none of which are very technical in nature. In no way does Postma undermine the existence or necessity of the greenhouse effect.