What is the problem with climate change?
It is causing more frequent and worse heat-waves, wildfires, floods, and storms. These impact human health, farming, fisheries, forestry, food security, infrastructure, drinking water supplies, and biodiversity. They cause social stress and have economic costs (including disaster relief, firefighting, lost crops, lost tourism, increased or no insurance cover). Extreme events such as heatwaves and wildfire smoke kill people (hundreds during late 2019 Australian wildfire, and thousands hospitalised). Air pollution from fossil fuels in cities also affects human health and mortality rates.
Infrastructure costs include damage and failure of electrical and communication services, sewage treatment, landfills, stormwater drains, roads, buildings, harbours, airports, railway lines.
A collection of photographs of 2021 heatwaves, wildfires, floods, landslides, cyclones and tornados around the world is here.
Biodiversity costs include loss of marine and terrestrial plant production, altered ecology perhaps favouring pest species and pathogens (viruses, bacteria, fungi, parasites), and further declines of threatened species.
These impacts get increasingly severe with more global warming and will affect everyone now and future generations.
Short video explainers from the BBC What is climate change? and Climate Check.The New York Times, and IPCC 6th Assessment Report 2021 with an independent “explainer“.
How can we know that once off extreme weather events are caused by anthropogenic climate change?
At first, it was not possible to know if extreme weather events, including heatwaves, droughts and floods were due to climate change. But looking back it seems these indicators began in the 1960s. Now, the increasing frequency and severity of extreme weather events that break new long-time records leave no doubt as to the cause. They are affecting both developed and developing countries. Warmer air absorbs more moisture and this falls as rain. Warmer oceans and land increase air thermals leading to stronger winds. Changing atmospheric circulation patterns change rainfall patterns in space and time. As time goes on and data accumulates it has become easier to attribute an extreme weather event to anthropogenic climate, as does the World Weather Attribution website.
What is the trend with greenhouse gases?
Their concentration in the atmosphere is at its highest for at least two million years. Half the releases from fossil fuel burning are captured in the oceans and on land, leaving half in the atmosphere.
That fossil fuel emissions of greenhouse gases cause global warming has been known since the late 1980s.
Greenhouse gas emissions have been rising since the late 19th century and their effects on the climate became increasingly apparent since the 1980s, but signs of it were there since the 1960s.
The Climate Clock calculates the time that the annual average temperature will take to reach 1.5 oC. IT accounts for recent emissions, and because these are continuing to increase, this time gets earlier than stated in IPCC reports.
Can we prevent climate change from getting worse?
Yes, by reducing its causes, namely the burning of fossil fuels. In addition, increasing carbon storage by vegetation on land and in the sea (e.g., forests, corals, shellfish, plankton that sink to the seabed) will reduce atmospheric carbon dioxide over time.
The longer society delays in addressing climate change the greater the costs to do so will be. Some economic assessments estimate that the cost of addressing greenhouse gas emissions is half the cost of doing nothing. The cost of keeping global warming to 2 oC is double the cost of keeping it to 1.5 oC.
The later reductions in greenhouse gas emissions are delayed the longer will be the withdrawal time it takes for atmospheric concentrations to decline. Even if emissions stopped now, it will take centuries to return to 1980s concentrations.
Can we not use technology to adapt to climate change?
Yes, technology will help, especially by replacing fossil fuel as an energy source with non-carbon emitting sources (e.g. solar, wind, wave and hydro-power). However, technological (e.g., air-conditioning) and infrastructure (e.g., sea walls) adaptations will become more expensive and not protect natural ecosystems or reduce natural disasters (fires, storms). Also, much of the hypothesised technologies do not exist or would be more expensive than converting society to non-fossil fuels earlier.
According to several eminent climate scientists, there is no proven way of achieving “net-zero” carbon dioxide to date. Thus, action is needed now to limit emissions because the amount of greenhouse gases needing to be addressed increases every day.
How much has the world warmed so far?
Global mean surface temperature (over land and sea) has risen by just over 1oC globally relative to the average from 1850 to 1900. Warming varies a lot geographically, being greater in the high latitudes of the northern hemisphere (Arctic region) and much less in the Southern Ocean. Most extreme temperatures are occurring in the low latitudes near the equator. However, New Zealand air temperatures have also warmed by 1oC from 1909 to 2018.
There has been greater warming over land (1.4oC) than the sea (0.8oC), but because the ocean occupies 71% of the planet it has a dominant influence on the global annual average temperature reported. This difference is because the ocean absorbs heat more slowly, and loses more heat through evaporation which is transported higher into the atmosphere through higher humidity above the ocean, more than land (Byne 2020). Thus, drier lands warm more.
How much has the sea level risen?
Globally, by 19 cm from 1901 to 2010, an average of 1.7 mm per year. The amount varies geographically due to land level changes and ocean height variation. In New Zealand, sea-level has risen faster, i.e., by an average of 2.4 mm per year from 1961 to 2018 (before 1960 it rose at 1.2 mm/year). In itself this seems insignificant but combined with high tides or storms, it means greater coastal flooding, landscape change and saltwater intrusion into wetlands. In New Zealand, the sea level will rise a further 0.2 to 0.9 m (above a 2005 baseline) by 2050 and 2100 respectively.
The combination of melting sea ice and glaciers, and ocean expansion as it warms has set in motion sea-level rise of mm per decade that will continue for centuries.
Is there any good side to global warming?
While there may be, on average, milder winters and less snow, the negatives greatly outweigh the positives. In some locations, this may lengthen the growing season in high latitudes, leading to early harvests, and increase decomposition rates. Russia may gain farmable land from the thawing of permafrost. This win/lose index shows how countries ability to adapt depends on both the degree of climate change and their preparedness.
Given good data on trends and understanding of ecosystems, it may be possible for farming and fisheries to adapt to climate change in some high latitudes, but not in low latitudes where it will be too hot. However, changes in atmospheric circulation may be resulting in more extreme cold weather in some regions such as northern America and Europe. These extreme events will have negative effects on farming as well as human health.
Although higher carbon dioxide levels can increase plant growth rates this requires more moisture on land and additional nutrients in the sea which are generally not available. Thus a carbon dioxide “fertilisation” effect is unlikely. Ocean phytoplankton productivity is predicted to decline due to climate change.
Why does global warming affect the weather?
Increased temperature results in more energy in the climate system. This manifests in stronger winds, greater evaporation of moisture from land and ocean leading to more clouds and extreme rainfall events, drier land and vegetation, longer droughts and more floods. One analysis indicates that weather conditions that promote wildfire in Australia are at least two times greater due to human-induced climate change; another that human-caused climate change has led to a 20 times increase in Marine Heat Waves.
Measurements show that wind speed has increased in line with climate change, leading to increases in ocean current speeds (circulation) detectable down to 2000 m depth.
What role has the ocean in climate change?
By absorbing about 90% of the energy from global warming the ocean greatly slows the rate of climate change. The ocean has also absorbed about 23% of the carbon dioxide emitted by human activities.
While the ocean has warmed by 1 oC since 1900, and the sea level has risen 25 cm since 1880, there is considerable geographic variation in warming and sea-level rise.
Warming reduces the concentration of oxygen in the ocean, reducing oxic habitat for most marine species. Contrary to popular statements, the ocean is not a net contributor to the oxygen we breathe as explained in this article.
Is there any scientific debate about whether global warming (climate change) is happening?
No. The climate data show it has been happening for decades. A few people (but not climate scientists) deny the role of our burning of fossil fuels as contributing to carbon dioxide and other greenhouse gases in the atmosphere (which is the cause of global warming and predicted decades ago). However, there is no other reasonable explanation for global warming, and carbon dioxide concentrations only make sense when fossil fuel burning is accounted for.
Understanding of the physics underlying how the sun warmed the Earth developed over 200 years ago (1820s). How carbon dioxide and other gases may cause a greenhouse effect was understood in the late 19th century. An appreciation of the significance of these greenhouse gases and the link to fossil fuel emissions emerged since the 1950s.
Good science distinguishes between the facts (data) and theories, the known and unknown, but also provides a reasoned argument (theory) as to cause and effect. As research progresses, some facts and theories become more certain and others are discarded. Each IPCC assessment has reassessed the facts and become more certain and the causes and projected effects of climate change.
How come the media portrayed uncertainty in whether fossil fuel emissions caused climate change?
There were organised fossil fuel industry supported campaigns to promote uncertainty so as to delay any action to reduce fossil fuel use. This strategy has been called the “tobacco playbook” following the success of the tobacco industry using naive, mistaken, poorly informed and compromised scientists to debate whether smoking was harmful. This debate suits the media need for controversy and provides a convenient excuse for people who do not want to change or have new regulations that affect their lifestyle. A nice rebuttal of the arguments against anthropogenic climate change is available on Skeptical Science and in a book detailing how a mix of industry lobbyists and others tried to deny the facts. Their tactics may now be shifting from denial to deflection and delay tactics, and/or rhetoric with no significant investment in real change.
Are there win-win-win solutions for biodiversity restoration and climate change adaptation and mitigation?
Yes, protected areas restore and conserve biodiversity which in turn captures and stores more carbon on land and sea. Soils, peatlands, and marine and freshwater sediments can be carbon sinks, sometimes called reservoirs and stores, because disturbance of these reservoirs may release greenhouse gases. Carbon dioxide and other greenhouse gases are also “stored” in water, with the ocean being the largest store by virtue of its size. Plants and other living matter also store carbon on a temporary basis.
Examples of “ecosystem-based management and adaptation“ are natural defences to reduce coastal erosion (e.g., mangroves, coral reefs), trees and parks that aid cooling in urban areas through shade and evapotranspiration, trees and vegetation that soak up water which is slowly released and reduces floods and droughts. Examples here for Australia.
How is progress in mitigating (reducing) the effects of climate change?
Not good at all. The black line on these graphs shows that trends in emissions are following the model (scenario) with the highest warming.
The global annual temperature has warmed by 0.3, 0.5, 0.7, 1.0 and almost 1.2 oC by 1980, 1990, 2000, 2010 and 2021 respectively, since pre-industrial times (1850-1900). About 0.2 oC per decade. Without zero carbon emissions from fossil fuels plus carbon removal from the atmosphere (for which no technology is currently operational at sufficient scale), the planet will warm to 1.5 oC by the early 2030s. as explained here.
What are the trends in emissions, impacts, and actions to reduce climate change?
The OECD Dashboard tracks these globally and nationally. The use of coal and oil is decreasing while renewable energy sources and natural gas is increasing. Energy use accounts for 80% of greenhouse gas emissions, industry 7% and agriculture almost 10%, and these vary by country.
The OECD Climate Action Monitor tracks the pledges by countries. In 2021 only 20% have made a zero-carbon pledge in law, another 20% proposed to and the remainder are considering it. These pledges only go a little more than halfway to meeting the targets necessary to curtail climate change. Lots of other interesting statistics here too.
What else is happening?
Increased carbon dioxide dissolved in the ocean as carbon acid is decreasing (acidifying) ocean pH. The ecological significance of this is a concern although unclear.
Unbelievably, governments continue to subsidise the use of the fossil fuels that are causing climate change.
What is the trend in evidence?
The evidence reviewed in each IPCC Assessment has confirmed the findings of its previous reports. The accumulation of field data improves predictions of future impacts of climate change. So now we know that the planet surface has warmed by an annual average of 1.2 oC since preindustrial times and is heading for 1.5 oC by the early 2030s (WMO 2021). Thus, extreme events such as heatwaves, floods, droughts, and wildfires, will increase in frequency and severity. Concurrently, the chronic effects of warming, glacier melting, ocean acidification and sea-level rise will accelerate. Hence the unprecedented global nature of the climate crisis is, directly and indirectly, affecting public health, business sector, property, infrastructure, food security and biodiversity. Adaptation by society may reduce such impacts, but only mitigation through reduced greenhouse gas emissions can reduce the occurrence of extreme events.
For the world:
IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp. Also available at https://www.ipcc.ch/report/ar5/syr/
United Nations Climate Action 2021. Key Findings.
For New Zealand: Ministry for the Environment. 2020. National Climate Change Risk Assessment for Aotearoa New Zealand: Main report – Arotakenga Tūraru mō te Huringa Āhuarangi o Āotearoa: Pūrongo whakatōpū. Wellington: Ministry for the Environment. Some interesting expert comments on the report.
A nice overview regarding New Zealand “Our atmosphere and climate 2020 summary“.
For Australia State of the Climate 2020 report with comments on the global situation. For 2021 it is a dramatic reading: “2019-20 was an exceptionally intense period for climate-fuelled extreme weather…. An extraordinary run of events, including unprecedented fire seasons in Australia and the US, a record-breaking North Atlantic hurricane season, and an astonishing series of heat records, paint a sobering portrait of our escalating climate crisis. The latest science projects that by 2100, annual deaths from extreme heat worldwide will outstrip all COVID-19 deaths recorded in 2020. The cost of extreme weather disasters in Australia has more than doubled since the 1970s, reaching $35 billion for the decade 2010-2019. Australians are five times more likely to be displaced by a climate-fuelled disaster than someone living in Europe. In the Pacific, that risk is 100 times higher.
Maps and data on climate change for Australia and globally.
Covid drove a record drop in fossil fuel emissions from transport in 2020, showing where transport emissions will improve air quality and reduce climate change.
For Ireland, more extreme weather events are driven by climate change and getting increasingly worse: Ireland’s climate: A year of extremes, from wettest February to driest spring (via @IrishTimes)
A horrifying vision for Australia at 3 oC by 2100 based on current (insufficient) plans to curb greenhouse gas emissions: The risks to Australia of a 3°C warmer world.
Byrne M. 2020. Why does land warm up faster than the oceans? Carbon Brief.
The Australian Climate Council produces information, news and advocates for addressing human-caused climate change.
World Meteorological Organisation 2021. State of the Global Climate 2020 (WMO-No. 1264).
Global emissions to hit 36.8 billion tonnes, beating last year’s record high
New research: nitrous oxide emissions 300 times more powerful than CO₂ are jeopardising Earth’s future
Eighteen countries showing the way to carbon zero [their emissions are declining]
Get a better understanding of the science of climate change in just 6 charts
What can we do to reduce effects of climate change? 11.5 min video from New Zealand (# 5 in the world in carbon emissions per capita)
“as the pandemic showed us, no one is safe unless we are all safe, and change is made by many, not a few.”
the pandemic “showed what can be done with concerted action”
“.. imagine if we had two years to prepare for ..” the pandemic (now we have years to prepare for climate change)
and a series 100 Years Forecast: A five-part documentary series on the impact of climate change for New Zealand’s future
Studying climate change is like watching somebody dying, reaching a point of inevitability when it is too late to stop it https://www.theguardian.com/australia-news/2020/oct/15/the-great-unravelling-i-never-thought-id-live-to-see-the-horror-of-planetary-collapse
How discussions around climate change need to be respectful, understanding and compassionate regarding other peoples viewpoints as well as getting the facts right https://theconversation.com/climate-explained-why-do-humans-instinctively-reject-evidence-contrary-to-their-beliefs-149436
Here’s a different way of looking at the same problem. https://www.eromangadisruption.com/
Calling a “climate emergency” only means the climate will be amongst other priorities a government will address. https://www.nzherald.co.nz/nz/analysis-what-does-declaring-a-climate-emergency-actually-do/6U3YQFOLDTZCCBWZ4ETXLHLDOE/
It does not mean urgent action will be taken to reduce emissions, like taxing fossil fuel emissions pollution, incentivising conversion to electric fleets, or dairy or beef to crops.
Seems there will be a new industry in putting CO2 back into the sea at 2500 m depth
All air temperature data sources show that 2020 was the warmest year on record in Europe, and with 2016 the warmest globally
2020 was tied with 2016 as the hottest year on record, and the warmest winter on record in New Zealand, and 6 of the 8 warmest years have occurred in the past 13 years. This presentation from NIWA shows images of drought, floods, insufficient snow for skiing, dust from Australian bush fires covering glaciers, and 47 consecutive months with temperatures above average for their month.
Thus clear evidence of climate change including warming and more extreme weather conditions.
Why are ocean warming records so important?
Reliable instrumental measurements stretch back to 1940 but it is likely the oceans are now at their hottest for 1,000 years and heating faster than any time in the last 2,000 years. Warmer seas provide more energy to storms, making them more severe, and there were a record 29 tropical storms in the Atlantic in 2020. Climate crisis: record ocean heat in 2020 supercharged extreme weather
How whales help cool the Earth by sinking carbon (their bodies) to the seabed and fertilising phytoplankton which in turn suck up carbon dioxide
Politicians need to heed that a world-wide a clear majority of all age groups in all countries amongst 1.2 million people polled by the United Nations Development Programme recognise the climate crisis as an emergency. The report can be downloaded here.
Australian business leaders rank climate change as a bigger problem for their industry than the covid-19 pandemic, in contrast to other countries where climate ranked third after covid and economy second
UN finds countries way off target to reduce greenhouse gas emissions. Current commitments will reduce emissions by 1% by 2030 when 45% is needed.
Easy read blog on Natural Climate Solutions https://www.conservation.org/blog/what-are-natural-climate-solutions#
UN chief says that coal is no longer an economically viable method to generate power, even without considering its effects on air pollution and greenhouse gas emissions. https://reneweconomy.com.au/un-demands-rich-countries-end-deadly-addiction-to-coal-by-2030/
Multiple catastrophic impacts of global warming on Australias biodiversity
Clever Haiku and art that summarises key messages from the IPCC AR5 (5th assessment report) https://www.sightline.org/2018/12/05/climate-change-told-in-19-heartbreaking-haiku/
Seabed trawling releases about as much CO2 (and probably methane) into the ocean as the global aviation industry as reported in The Guardian
Radio New Zealand
Carbon farming is profitable
The “Shared Socioeconomic Pathways’ models for how society may develop under climate change are explained here
Best explanation of RCP, SSP, IAM, CMIP and other jargon I have found from Explainer: The high-emissions ‘RCP8.5’ global warming scenario:
…out of the four integrated assessment models (IAMs) used to create the RCP scenarios, only RCP8.5 was a “baseline” scenario that included no policy-driven mitigation …
“RCP8.5 should be seen as a high emission scenario” while “RCP6.0 can be interpreted as either a medium baseline or a high mitigation case”. This suggests that the authors say no reason to consider RCP8.5 a more likely “business as usual” outcome than, say, RCP6.0. ….
“RCP8.5 was never meant to be a business-as-usual scenario, but as a high-end scenario, consistent with the highest emissions scenarios in the literature.
RCP 8.5 “it is more properly considered to be one of the worst case emissions outcomes, as according to van Vuuren and colleagues, more than 90% of the other no-policy baseline scenarios in the literature result in lower emissions.”
The SSPs contain a range of baseline scenarios spanning between 5.0 and 8.5 W/m2 of radiative forcing by 2100.
CMIP6 will include the same four forcing levels found in the RCPs – 8.5, 6.0, 4.5, and 2.6 – in addition to new 1.9, 3.4 and 7.0 forcing scenarios. Both the 8.5 and 7.0 scenarios are taken from no-policy baseline emission scenarios in the SSP database, while all the other forcings use emissions scenarios where some level of mitigation is employed.
economist Bill Nordhaus argued that the world has a 35% chance of exceeding RCP8.5 by the end of the century. While most energy researchers think emissions of the magnitude in RCP8.5 are quite unlikely, they are by no means impossible.
there have been some claims – prominently in the US Fourth National Climate Assessment – that current emissions are tracking the RCP8.5 scenario.
While climate change is accepted by most people it is not their top priority for politicians https://theconversation.com/most-people-consider-climate-change-a-serious-issue-but-rank-other-problems-as-more-important-that-affects-climate-policy-161080
Australian court judge finds that climate change “might fairly be described as the greatest inter-generational injustice ever inflicted by one generation of humans upon the next” https://theconversation.com/in-a-landmark-judgment-the-federal-court-found-the-environment-minister-has-a-duty-of-care-to-young-people-161650
The court then ruled that the government Minister responsible for permitting coal mining has a “duty of care” to future generations. Thus, they would be negligent if they allow further coal mining.
The chemists suggest taking carbon dioxide out of the ocean because it is 150 times more concentrated there than in air and letting the ocean continue to reabsorb it from hate atmosphere
Increasingly commentators note that the IPCC process is conservative in depending on multiple peer-reviewed studies to make “confidence” statements, and did not predict the scale of 2019-2020 wildfires in Australia and 2021 2m+ high floods in Germany and neighbouring countries https://www.bbc.com/news/science-environment-57863205
How an extreme event is attributed to anthropogenic climate change https://www.worldweatherattribution.org/pathways-and-pitfalls-in-extreme-event-attribution/
Video compilation of July 2021 extreme weather events around the world which are examples of how climate change can affect at local scales
Leaked IPCC reports highlight climate change is happening faster than expectations and radical action to reduce greenhouse gas emissions is needed within this decade to prevent warming above 1.5 oC
Study on Climate Journalism in New Zealand is online
The popular narrative that climate change sea-level rise is going to swamp islands is not true. Some islands may be inundated but other islands are growing.
Climate caused wildfire smoke releases both carbon dioxide and iron that fertilises phytoplankton in the ocean
How to better communicate about climate change from Arnold The Terminator
Great speech by David Attenborough to the 2021 climate COP
Video explains how the warm planet tens of millions of years ago compares to climate change today
Commentary in The Conversation on the movie “Don’t look up!” satirising the climate change inaction by governments and more here in The Guardian.
The Earth Negotiations Bulletin provides summaries of IPCC and other reports https://enb.iisd.org/55th-session-intergovernmental-panel-climate-change-ipcc-55-12th-session-working-group-II-summary, including detailed report of proceedings and summary of it
Comments on the 2022 IPCC WG2 report on the national broadcaster in Ireland https://www.rte.ie/news/world/2022/0316/1286787-climate-change-report/#
Climate analogues are places that are the same (analogous) climate. Due to climate change, these places are moving. This app shows how with and without reductions in greenhouse gas emissions how North American city’s climates will be the same as another place in the future https://fitzlab.shinyapps.io/cityapp/