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).
Infrastructure costs include damage and failure of electrical and communication services, sewage treatment, landfills, stormwater drains, roads, buildings, harbours, airports, railway lines.
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.
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.
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.
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).
How much has the world warmed so far?
By just over 1 oC globally since the late 19th century. Warming varies a lot geographically, being greater in the high latitudes of the northern hemisphere and much less in the Southern Ocean. However, New Zealand air temperatures have also warmed by 1 oC from 1909 to 2018.
How much has 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, sea level will rise a further 0.2 to 0.9 m (above a 2005 baseline) by 2050 and 2100 respectively.
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 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 areas. 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.
What role has the ocean in climate change?
By absorbing about 90% of the energy from global warming it greatly slows the rate of climate change. 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.
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.
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. Their tactics may now be shifting from denial to deflection and delay tactics.
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.
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,
Further reading
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/
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)
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