Why hot weather records continue to tumble worldwide

Andrew King, University of Melbourne

It sometimes feels like we get a lot of “record-breaking” weather. Whether it’s a heatwave in Europe or the “Angry Summer” in Australia, the past few years have seen temperature records tumble.

This is the case both locally – Sydney had its hottest year on record in 2016 – and globally, with the world’s hottest year in 2016 beating the record set only the year before.

Some of 2016’s heat was due to the strong El Niño. But much of it can be linked to climate change too.

We’re seeing more heat records and fewer cold records. In Australia there have been 12 times as many hot records as cold ones in the first 15 years of this century.

If we were living in a world without climate change, we would expect temperature records to be broken less often as the observational record grows longer. After all, if you only have five previous observations for annual temperatures then a record year isn’t too surprising, but after 100 years a new record is more notable.

In contrast, what we are seeing in the real world is more hot temperature records over time, rather than less. So if you think we’re seeing more record-breaking weather than we should, you’re right.

Why it’s happening

In my new open-access study published in the journal Earth’s Future, I outline a method for evaluating changes in the rate at which temperature records are being broken. I also use it to quantify the role of the human influence in this change.

To do it, I used climate models that represent the past and current climate with both human influences (greenhouse gas and aerosol emissions) and natural influences (solar and volcanic effects). I then compared these with models containing natural influences only.

Lots of hot records, fewer cold ones

Taking the example of global annual temperature records, we see far more record hot years in the models that include the human influences on the climate than in the ones without.

Crucially, only the models that include human influences can recreate the pattern of hot temperature records that were observed in reality over the past century or so.

Observed and model-simulated numbers of hot and cold global annual temperature records for 1861-2005. Observed numbers of record occurrences are shown as black circles with the model-simulated record numbers under human and natural influences (red box and whiskers) and natural influences only (orange box and whiskers) also shown. The central lines in the boxes represent the median; the boxes represent interquartile range.
Author provided

In contrast, when we look at cold records we don’t see the same difference. This is mainly because cold records were more likely to be broken early in the temperature series when there were fewer previous data. The earliest weather data comes from the late 19th century, when there was only a weak human effect on the climate relative to today. This means that there is less difference between my two groups of models.

In the models that include human influences on the climate, we see an increase in the number of global record hot years from the late 20th century onwards, whereas this increase isn’t seen in the model simulations without human influences. Major volcanic eruptions reduce the likelihood of record hot years globally in both groups of model simulations.

Projecting forward to 2100 under continued high greenhouse gas emissions, we see the chance of new global records continuing to rise, so that one in every two years, on average, would be a record-breaker.

Chance of record hot global annual temperatures in climate models with human and natural influences (red) and natural influences only (orange). Grey curve shows the statistical likelihood of a new hot record each year (100% in the first year, 50% in the second year, 33% in the third year, and so on). Grey vertical bars show the timing of major volcanic eruptions through the late-19th and 20th centuries.
Author provided

I also looked at specific events and how much climate change has increased the likelihood of a record being broken.

I used the examples of the record hot years of 2016 globally and 2014 in Central England. Both records were preceded by well over a century of temperature observations, so in a non-changing climate we would expect the chance of a record-breaking year to be less than 1%.

Instead, I found that the chance of setting a new record was increased by at least a factor of 30 relative to a stationary climate, for each of these records. This increased likelihood of record-breaking can be attributed to the human influence on the climate.

More records to come?

The fact that we’re setting so many new hot records, despite our lengthening observation record, is an indicator of climate change and it should be a concern to all of us.

The increased rate at which we are getting record hot temperatures is controlled by the speed of global warming, among other factors. To meet the Paris target of keeping global warming below 2℃ we will have to reduce our greenhouse gas emissions drastically. Besides keeping average global temperatures under control, this would also reduce the chance of temperature records continuing to tumble, both globally and locally.

Andrew King, Climate Extremes Research Fellow, University of Melbourne

This article was originally published on The Conversation. Read the original article.

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Put out water for the wildlife in your garden on hot days

Susan Lawler, La Trobe University

Wildlife need water on hot days.
Melanie Thomas, from pixabay.com

Last night I was watering the garden with a hose. It is easy to see how stressed the plants are on a 38 degree day, but then I remembered that the animals in my garden need water too. So I filled some shallow bowls and placed them in quiet shady spots. During a hot Australian summer day, such an act can save a life. A small life, perhaps, but every little bit counts.

I have a small suburban garden but it still supports a range of insects, birds, frogs and reptiles. Whenever we move a pile of wood we disturb some lovely spotted geckos. Even in the city most Australians will have possums moving through the trees and skinks sheltering under the back steps. Suburbs on the edge of town have wombats, wallabies and kangaroos. Birds and insects live everywhere. On hot days all creatures will seek water and shade.

So why not add a routine to your normal gardening chores and put out some water for wildlife? Here are a few hints to ensure that the animals benefit.

Tips for watering wildlife

Use only shallow bowls so small animals do not drown. Alternatively (or additionally) add a few rocks or sticks so they can easily crawl out. Do not use metal bowls as these will become hot and may burn their feet or paws. Place the water in a shady spot, out of the way of human activity and protected from domestic pets.

Birds and tree dwelling animals will appreciate water hung at various levels. You can nail a plastic tub to a fence, or hang a modified water bottle in a tree.
If you are able to set up a hose to mist a shady corner in the garden, you will create a small haven for wildlife. I did this last night with the excuse that the lemon tree needed a good drink anyway.

Don’t worry if you don’t see the animals using your water. It is likely that they prefer privacy and will use it when you are not looking.

On the other hand, if you do see animals showing signs of heat stress, you may have to take further steps.

Caring for heat stressed wildlife

Animals that are suffering from heat stress will behave strangely. Nocturnal animals that are out during the day, tree dwelling animals sitting on the ground, or animals that are lethargic or staggering are all showing signs of stress.

The first concern about stressed wildlife is your own safety. Do not approach snakes, flying foxes, large kangaroos, eagles, hawks or goannas. Your best bet is to contact a trained wildlife carer for advice.

It is a good idea to have the phone numbers of your local wildlife carers handy, or download the wildlife rescue app.

If it is safe to do so, you can assist a heat stressed animal by picking it up in a towel, placing it in a well ventilated box in a cool spot and provide water. Do not feed the animal or handle it more than necessary. The animal may recover enough to release again in the evening, but if not you will need to take them to a wildlife carer or a vet.

Wildlife and bushfires

Unfortunately many Australians now live under the threat of bushfires and face evacuations throughout the summer months. Obviously, fires are bad for both domestic and wild animals. The best thing you can do during an evacuation is to take your dogs and cats with you and leave out plenty of water for wildlife.

If you do find injured wildlife, take them to the vet if it is safe to do so. Never go into a fire affected area searching for injured animals. This is a job best left to trained staff who are coordinated by the appropriate agencies and assisted by volunteers who have had the right training.

On the other hand, all of us can help by putting out water for wildlife. Every little bit helps.

Susan Lawler, Senior Lecturer, Department of Ecology, Environment and Evolution, La Trobe University

This article was originally published on The Conversation. Read the original article.

The oceans are becoming too hot for coral, and sooner than we expected

Ove Hoegh-Guldberg, The University of Queensland

This week, scientists registered their concern that super-warm conditions are building to a point where corals are severely threatened across the tropical Indian, Pacific and Atlantic oceans. They did so after seeing corals lose colour across the three major ocean basins – a sign of a truly momentous global change.

This is only the third global bleaching event in recorded history.

Underwater heat waves

The situation has been worrying scientists like myself for many months. Over the past 12 months, the temperatures of the upper layers of the ocean have been running unseasonably warm. Underwater heatwaves have torn through these tropical regions over summer, and corals across large areas of reef have lost their colour as the algal partners (or symbionts) that provide much of the food for corals have left their tissues. Bereft, corals are beginning to starve, get diseased and die.

The “heatwaves” that are causing the problem are characterised by extremes that are 1-3 degrees C warmer than the long-term average for summer. It doesn’t seem like much but past experience has shown us that exposure to small increases in temperatures for a couple of months is enough to kill corals in great numbers.

In the first global mass bleaching event in 1998, regions such as Okinawa, Palau and north-west Australia lost up to 90% of their corals as temperatures soared.

By the end of 1998 up to 16% of the corals on the world’s tropical reefs had died.

The key concern here is that corals are not an inconsequential part of the biology of the ocean. While geographically insignificant (less than 0.1% of the ocean), coral reefs punch well above their weight in terms of their importance to the ecology of the ocean and to humans.

Over a million species are thought to live in and around coral reefs, while an estimated 500 million people derive food, livelihoods and other benefits from coral reefs throughout the tropics.

Why the heatwaves?

Warm conditions were seen across the ocean in 2014, with an on-again off-again El Niño condition in the Pacific and similar conditions across Indian and Atlantic-Caribbean ocean regions.

As a result, surface waters came close to triggering mass coral bleaching in many places, and did trigger bleaching in many others. The equatorial Pacific, for example, experienced bleaching temperatures from April without relent, generating reports of extensive bleaching and mortality.

One question that is on everyone’s lips is, why the elevated temperatures?

At one level, the drivers for the current global bleaching event are clear. Climate change has been driving up sea temperatures. When natural variability adds to this trend, such as during El Niño, temperatures now exceed the threshold for mass coral bleaching and death.

This explanation has been sufficient for the last couple of decades. I have used it many times.

However, that may be changing as we learn that the intensity of El Niño may well also be vulnerable to changes in average global temperatures. A growing number of studies (see also here) are showing that strong El Niño are becoming more frequent, and climate change is likely a significant driver of this. This and phenomena such as the mysterious warm patch) in the eastern Pacific (nicknamed the “Blob”) suggest the simple model may need to be modified.

The Coral Reef Watch program run by the US National Oceanic and Atmospheric Administration (NOAA) has developed a number of models to estimate the likelihood of mass coral bleaching and mortality, as you can see in the figure below.

Projections of stress – NOAA
NOAA Coral Reef Watch

These models show considerable ability to predict where, when and how severe mass coral bleaching and mortality are likely to be. Looking at these projections reveals the spread of underwater heatwaves and the risk of mass coral bleaching and mortality.

Have we under-estimated the risk of a changing ocean?

Understanding the sensitivity of reef-building corals to elevated temperatures allows us to ask the question: if sea temperatures are increasing, when does it get too hot for corals every year in the future? I did this some years ago and came up with the answer that most oceans get too hot for their corals on a yearly basis by 2040-2050.

At the time, this was quite shocking – the idea that corals would be eliminated by mid-century. All those species, all those resources for people.

The problem is, I was only accounting for a doubling of greenhouse gases, as opposed to the tripling or more under the current business-as-usual approach, and the models used for estimating future sea temperatures didn’t account for more frequent extreme El Niño. And if so, then my original projections of when the oceans become too hot for coral reefs are too optimistic!

The current looming global stress event certainly emphasises this story. As I look at NOAA’s stress maps, I am reminded of the huge and unprecedented experiment that we are running. I am also conscious that the consequences of warming have been underestimated for almost everything we look at. I am compelled to question whether the negotiators headed for meeting in Paris in a month or so really appreciate the urgency.

Do they know that we need to pull the plug immediately on this crazy experiment? Given that the current pledges going into Paris are so woefully inadequate, it would seem not.

Perhaps we now have to hope that the dying gasps of the world’s most diverse marine ecosystem can jolt our negotiators into action. If not, then it would seem that nothing will.

Ove Hoegh-Guldberg, Director, Global Change Institute, The University of Queensland

This article was originally published on The Conversation. Read the original article.

NSW Road Trip 2010: Packing & Getting Ready

It is now the day prior to the NSW Road trip 2010. I have begun packing and getting ready for the journey that lies ahead. I don’t expect to be taking a lot of gear, as I won’t be doing a lot of cooking, washing, etc, on this trip.

I have learnt that it is important to not assume that you have everything you need and then find out the day before that you may not – I already knew this of course, but having recently moved, I no longer have everything that I once did. For example, I do not presently have a sleeping bag. I got rid of the last one because it was old and smelly, and I planned to buy another. But a lot has happened since mid 2007 when I packed to move – including a near fatal car accident that put my purchasing plans well and truly on hold, and they then slipped into the area of my mind that ‘forgets.’

So now I have no sleeping bag – but that isn’t too important as I don’t believe I really need one this time round. It is a road trip, with several cabin stops along the way and only caravan parks with powered sites for the rest. I will take a couple of blankets should I need them (which I don’t believe I will – it will be quite hot in the outback this time of year).

Of course it is not just the sleeping bag that is missing. I am also missing a fly cover for the tent, but thankfully I had two tents so I’m OK there. There are a number of other items missing also, but I don’t really need them this time round. Thankfully I have spotted all this now, which means I can plan to purchase what I need for future adventures, back pack camping, etc. I had of course planned to buy these items, but with the passing of time I forgot.

Anyhow, the packing is under way and I just hope I don’t forget something I wish I had packed when I am on the journey. I’m relatively sure I haven’t – which isn’t to say That I have forgotten something.

What I’d like to remember – and tomorrow I’ll know for sure if I have – is how I packed the car, so that everything was easily accessible. I was fairly well organised for this sort of thing when I was doing it fairly regularly several years ago – but it has been a while. Minimal gear wisely packed, without leaving anything necessary behind – that’s the key for this type of journey and vacation.

This will be the first time however, that I have a bag dedicated to my online activities – laptop, digital camera, web cam, flash drives, etc. I hope to keep an accurate and useful journal online at the kevinswilderness.com website, with photos, comments, route map, etc. So this is a ‘new’ bag that I need to organise in the overall scheme of things.

Anyhow, packing is now underway and coming to a conclusion. The journey will soon kick off.

Holiday Planning: Progress is Being Made

I have been doing a little work on the planning side of things for my holiday. There have been some changes and these will be explained below.

Firstly, I have decided to push the holiday back a bit. There are a few public holidays during January 2010, so I think I can cope with a few extra weeks at work before needing the break. So instead of taking the holiday at the start of February, I am thinking of taking the holiday for two weeks in late February – early March 2010, or maybe a week or so later than that.

The later time for the holiday will also allow me to save for the trip and ensure I have everything I want for the holiday. I may even be able to get a digital video camera by then, which will be a great plus.

Secondly, the destination has also changed. I won’t be going out west as temperatures out that way are sure to be very hot and somewhat unbearable for any bushwalks I would want to do. The out west option will need to be looked at for a winter holiday (even though night temperatures are bound to be quite cold then). I do have a plan underway for that option also, which will probably mean a holiday in about August – September 2010 (but that is another story for another time). So to make sense of these two possible (probable) holidays in my Blog posts, the earlier holiday will be called the summer holiday 2010 and the later the winter holiday 2010.

So instead of going way out west for the summer holiday 2010, I’m thinking of going west a little (and to the south), before heading back to the southeast and travelling through the far southeast of New South Wales.

Are there any solid plans? Solid may not be quite the word for it, but I am settling on what I’d call a fairly sure itinerary for the first couple of days of summer holiday 2010. The date is certainly not fixed and that is really quite flexible at the moment. The itinerary for the first few days will probably be:

Day 1 Destination – Dubbo

Day 2 Destination – Conimbla National Park

Day 3 Destination – Wagga Wagga

So the next stage of planning will be to iron out the itinerary for these first three days before moving on towards my planned far southeast New South Wales travels.

For information on Conimbla National Park:

http://www.environment.nsw.gov.au/NationalParks/parkHome.aspx?id=N0053