Week 3: Reflect

Consider:

1. What are the most important themes you have learned this week?

That there has been a huge rise in CO2 and global temperatures, The 'Hockey Stick' graph backs this up, it is interesting that 10% of the CO2 contribution is deforisation and 90% is burning fossil fuels.

1. What aspect of this week did you find difficult?

It is hard finding the time to take in the course in as much detail as I would like.

1. What did you find most interesting? And why?

How the deep ocean stores carbon.

1. Was there something that you learned this week that prompted you to do your own research?

Expanding and Melting Artic ice.

1. Are there any web sites or other online resource that you found particularly useful in furthering your knowledge and understanding?

all the websites provided.

 

Week 3: Summary

Antarctic sea ice reached a record maximum in 2012, how is this best explained?

Recent increases in circumpolar wind strength has blown the sea-ice outward so extent has increased.

What is the current atmospheric concentration of carbon dioxide in parts per million (ppm)?

400 ppm

Which of these countries has the highest carbon emissions per capita?

USA

Which of these is the largest carbon store?

Deep ocean
 

Why is the Arctic experiencing the largest warming on Earth?

Ice-albedo feedback

Week 3: Global Carbon Emissions

Week 3: Our Changing Carbon Cycle

·         How human activity has contributed to an atmospheric concentration of carbon dioxide not seen since the Pliocene epoch between 2.6 and 5.3 million years ago.

·         The climate has been changing dramatically over the last 100-150 years.

·         This isn’t due to just natural variability in a system, it involves other components uh as emissions of greenhouse gases.

·         Carbon dioxide is one of the key gases that cause the warming blanket.

·         1 PgC = 10¹⁵ gC, 10PgC of carbon are released into the atmosphere ever year due to human activity.

·         90% of the emission of CO² comes from the burning of fossil fuels the remaining 10% comes from deforestation.

·         The main countries emitting CO² are USA, Europe and Japan, emerging countries like china and india are also contributing.

·         For deforestation the main emitters are European countries in the tropics such as brazil or Indonesia.

·         CO² emissions are above 10PgC per year.

·         The atmospheric increase in CO² is about 4.5 PgC per year.

·         The remainder of the CO² is absorbed by the land and the ocean.

Week 3: Urgent Action

http://sciencepolicy.agu.org/files/2013/07/AGU-Climate-Change-Position-Statement_August-2013.pdf

·         Human Activities are changing earth’s climate.

·         At the global level, atmospheric concentrations of carbon dioxide and other heat-trapping greenhouse gases have increased abruptly since the industrial revolution.

·         Fossil fuel burning dominates this increase.

·         Human-caused increases in greenhouse gases are responsible for most of the observed global average surface warming.

·         Natural processes cannot quickly remove some of these gases (notably carbon dioxide) from the atmosphere, our past, present and future emissions will influence the climate system for millennia.

·         ‘Extensive, independent observations confirm the reality of global warming’ – American Geophysical Union

·         Theese observations show large-scale inceases in air and sea temperature, sea level, and atmospheric water vapour, they document decreases in the extent of mountain glacier, snow cover, permafrost, and Artic sea ice.

·         Theese changes are broadly consistent with long understood physics and predications of how the climate system is expected to respond to human-caused increases in greenhouse gases.

·         The changes are inconsistent with explanations of climate change that rely on known natural influences

·         Climate models predict that global temperatures will continue to rise, with the amount of warming primarily determined by the level of emissions. Higher emissions of greenhouse gases will lead to larger warming, and greater risks to society and ecosystems.

·         Some additional warming is unavoidable due to past emissions.

·         Climate change is not expected to be uniform over space or time. Deforestation, urbanization, and particulate pollution can have complex geographical, seasonal, and longer‐term effects on temperature, precipitation, and cloud properties.

·          Human‐induced climate change may alter atmospheric circulation, dislocating historical patterns of natural variability and storminess.

·         In the current climate, weather experienced at a given location or region varies from year to year; in a changing climate, both the nature of that variability and the basic patterns of weather experienced can change, sometimes in counterintuitive ways ‐‐ some areas may experience cooling, for instance. This raises no challenge to the reality of human‐induced climate change.

·         Impacts harmful to society, including increased extremes of heat, precipitation, and coastal high water are currently being experienced, and are projected to increase.

·         Other projected outcomes involve threats to public health, water availability, agricultural productivity (particularly in low‐latitude developing countries), and coastal infrastructure, though some benefits may be seen at some times and places.

·         Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels.

·         While important scientific uncertainties remain as to which particular impacts will be experienced where, no uncertainties are known that could make the impacts of climate change inconsequential.

·         Furthermore, surprise outcomes, such as the unexpectedly rapid loss of Arctic summer sea ice, may entail even more dramatic changes than anticipated.

·         Actions that could diminish the threats posed by climate change to society and ecosystems include substantial emissions cuts to reduce the magnitude of climate change, as well as preparing for changes that are now unavoidable.

·         The community of scientists has responsibilities to improve overall understanding of climate change and its impacts. Improvements will come from pursuing the research needed to understand climate change, working with stakeholders to identify relevant information, and conveying understanding clearly and accurately, both to decision makers and to the general public.

 

Adopted by the American Geophysical Union December 2003; Revised and Reaffirmed

December 2007, February 2012, August 2013.

Week 3: Warming World

What places on Earth have experienced the largest warming from 1980-2004? Are the areas that are experiencing the most warming also showing the largest variability in temperature and or precipitation?

The overall trend of temperature across the globe is that the northern hemisphere will experience higher temperature values for the 2050-2074 climate scenario, with most northern countries (Iceland, UK, US, Canada, Russia, Mongolia, China) experiencing an average temp increase of more than 2 degrees C. This seems to be in contrast with countries in the southern hemisphere whose temperature increase for the 2050-2074 climate scenario only reaches a maximum of 1.6 dgr C (i.e. Brasil), or it will 'only' increase to 1.1 dgr C (i.e. New Zealand).

Week 3: State of The Climate: Extreme Events

A major climate event near me is 2012 brought the UK's second wettest weather on record.



http://nsidc.org/news/press/20121002_MinimumPR.html

Week 3: How Has Our Climate Changed?

Source: Met Office

December 2013

The global average temperature for December 2013 was 0.49 ± 0.15 °C above the 1961-1990 average (down slightly from November). Sea-surface temperatures (SSTs) in the Tropical Pacific remained close to the long-term average, but together with other indicators, conditions were still El Niño-Southern Oscillation (ENSO) neutral.

During December, the global average air temperature over land was warmer than the long-term average. The pattern of temperature anomalies in the northern hemisphere bore certain similarities to November. Northern Eurasia was much warmer than average, but cooler than average conditions were reported in southern parts of the continent. Much of the US and Canada were colder than average, but Alaska and parts of the west coast were warmer than average. South America was largely warmer than average, but the far southern tip and the Antarctic Peninsula were colder than the long-term average.

SSTs were generally warmer than average. Areas of cooler than average SSTs were recorded in the eastern Pacific, south Atlantic and Southern Oceans. Unusually high water temperatures were recorded in the north Pacific, north Atlantic and western Pacific.

December 2011

The global annual average temperature for 2011 was estimated to be between 0.35 and 0.45 °C above the 1961-1990 average according to figures from theHadCRUT3,  NOAA NCDC and  NASA GISSanalyses. This places 2011 among the 15 warmest years and most likely between the 9th (HadCRUT3) and 12th (GISS) warmest. Although 2011 was significantly warmer than the average for the 1990s, it was cooler than average for the 2000s. The cooling relative to recent years is partly due to the double La Niñas which bookended 2011.

La Niña conditions continue, but have shown signs of weakening over the past few weeks, with sea-surface temperatures in the eastern Pacific returning to near normal. Further west, however, sea surface temperatures remain close to La Niña thresholds.

In December significant warmth - temperatures exceeding the 90th percentile - were recorded over large areas of Europe, Canada and northern Eurasia. Areas of the western Pacific, north Atlantic and Indian Ocean were also significantly warm. Significant cold - temperatures below the 10th percentile - were recorded across Australia, parts of the Eastern Pacific, a region east of the Caspian Sea, in the South Atlantic and along parts of the Antarctic coastline.

http://www.metoffice.gov.uk/research/monitoring/climate

Week 3: Signals of Climate Change

What evidence do we have of the singles of climate change, including an increase in extreme weather events?

 

·         Observing weather has led to key indications of climate change

·          As time has progressed weather data has become more reliable.

·         On land we measure using thermometers inside Stevenson screens, which shield the thermometers from the direct effects of radiation and rainfall.

·         Meteorological temperatures are always measured in the shade, and those are the temperatures weather forecasters predict.

·         We regularly collect observation in temperature rainfall ect.

·         Sometimes balloons are using to collect a 3d view of weather

·         And we have submarines

·         Key weather changes of climate change: global mean temperature over land and ocean, recent ocean is warmest overall.

·         Steady rise in sea level half due to thermal expansion and half due to melting land ice.

·         Melting sea ice does not contribute to sea level rise.

·         Temperatures have been highest in polar arctic region.

·         The surface of arctic sea ice in summer has dropped from around 4m square kilometres to around 1.5m square kilometres.

·         Its difficult to say wither tornados, tsunamis are part of a long term climate change signal or just natural fluctuations.

·          

Week 2 & 3: Tim Lenton

Carbon – it’s the favourite element of many Earth system scientists, and the last two weeks of the course have both included bits about the global carbon cycle. I’ve been impressed by some of the interesting questions this has raised, so let me try and join some of the dots.

Week 2 introduced the long-term geological carbon cycle in which carbon dioxide is added to the atmosphere by volcanoes and metamorphic processes (the heating and pressurising of sedimentary rocks, which cooks out some of the carbon they contain). This input of carbon dioxide is balanced, over geologic timescales (here we’re talking about a million years or more) by an equivalent output of carbon dioxide. That output is due to the process of weathering, which liberates calcium and magnesium ions from silicate rocks, followed by the combination of those ions with carbon dioxide to form new carbonate rocks, deposited as sediments at the bottom of the ocean. (The chemically minded can think of this as, e.g.: CaSiO3 + CO2 => CaCO3 + SiO2.)

You might be wondering how the output of CO2 comes to balance the input? The answer is that the rate of silicate weathering is sensitive to the CO2 content of the atmosphere and the resulting temperature. If for example, volcanic activity increases and more CO2 enters the atmosphere, then CO2 and temperature levels will go up, but this leads to more silicate weathering and CO2 removal, until the system stabilises with the ‘sink’ for CO2 again matching the ‘source’.

Occasionally people ask if this negative feedback process will come to the rescue and balance our ‘anthropogenic’ CO2 emissions? The answer is: only very slowly! The removal of CO2 by silicate weathering is a tiny amount each year compared to the input of CO2 from fossil fuel burning. If left to natural processes (rather than geoengineers), it will take nearly a million years for accelerated silicate weathering to drag atmospheric carbon dioxide back down to its pre-industrial concentration.

In the meantime we need to think about much shorter-term processes in the global carbon cycle that are responding to our CO2 emissions, and that’s what Week 3 has tackled. To get a handle on this it first pays to know where carbon likes to live – a huge amount of it favours the deep ocean – 38,000 billion tonnes in fact. That is because carbon dioxide reacts with seawater and the resulting acid then dissociates into various dissolved forms (for the chemists: CO2 + H2O <=> H2CO3 <=> H + HCO3 <=> 2H + CO3). Roughly 2,000 billion tonnes of carbon are stored in all the vegetation and soils of the world. And before we started meddling with it, the atmosphere contained 600 billion tonnes of carbon.

Between each of these ‘reservoirs’ of carbon there are natural exchange fluxes. Roughly 100 billion tonnes of CO2 come out of the ocean each year and 100 billion tonnes go back in. It’s a similar story for the land surface, where CO2 goes into plants (through photosynthesis) and comes out again from plants, animals and fungi due to respiration (much of it from the breaking down of organic matter in soils).  The crucial thing is that these exchange fluxes are naturally in balance.

When humans add CO2 to the atmosphere – most of it extracted as fossil fuels from the Earth’s crust – this creates an imbalance. The extra concentration of CO2 in the atmosphere makes both the land and the ocean take up more CO2. About a quarter of the CO2 we add to the atmosphere each year reacts with seawater and enters the ocean. Another quarter is taken up by plants, partly because photosynthesis works more efficiently in an atmosphere richer in CO2. These are referred to as the land and ocean ‘carbon sinks’, and we should be thankful to them every day, because without them the climate change challenge would be twice as large.

Several of you have been asking how these sinks might change in the future, as CO2 carries on going up and the world gets warmer? Of course we would like the sinks to grow, and whilst CO2 emissions keep increasing we expect the ocean sink at least to grow in absolute size. But the fraction of annual CO2 emissions that go into the ocean is expected to decline. That is because adding CO2 has the effect of acidifying the ocean and making it less able to take up extra carbon. Also warming makes CO2 less soluble in water (thinking of warming up a fizzy drink and watching it go flat). All this means that we cannot expect the ocean to mop up all of our CO2 pollution. When we have finished burning fossil fuels and adding CO2 to the atmosphere, and we have given the ocean time to find a new balance – which means in about the year 3000 AD – we expect somewhere between 20% and 40% of the CO2 we have emitted to still be in the atmosphere. The percentage gets larger the more CO2 we emit.

What about the land? Well, that is more uncertain. In the best case scenario the land will continue to take up CO2, but its storage capacity for carbon will saturate, and a new balance will be struck with more carbon in vegetation and soils than now. However, warming tends to reduce the storage of carbon on the land, because it accelerates respiration. Also frozen soils – the permafrost – may thaw and release some of its stores of carbon to the atmosphere. And fires may become more frequent and devastating in a warmer climate, returning more CO2 to the atmosphere via combustion. In the worst case scenario, the land could switch from being a sink to a net source of CO2 to the atmosphere. If that happens, we will have only the ocean to counteract the rise of CO2.

What we are talking about here are climate feedbacks involving the carbon cycle, and they are very topical. This week both Pierre Friedlingstein and I found ourselves having breakfast in the UK parliament talking about such feedbacks, because we helped out with a note on the topic of ‘Risks from Climate Feedbacks’ written for our politicians:

http://www.parliament.uk/briefing-papers/POST-PN-454/risks-from-climate-feedbacks

MOOC participants will hopefully be pleased to know that the MPs and peers present were very interested to hear about our course and the discussions it is triggering. You never know, perhaps one or two have even signed up…

Professor Tim

PS If you are wondering why it took me two weeks to write another blog entry, my excuse is I had to mark 240 exam scripts, which if nothing else revealed that my undergraduate class are wrestling with the carbon cycle as much as you are

Week 2: Reflection

1. What are the most important themes you have learned this week?
2. What aspect of this week did you find difficult?
3. What did you find most interesting? And why?
4. Was there something that you learned this week that prompted you to do your own research?
5. Are there any web sites or other online resource that you found particularly useful in furthering your knowledge and understanding?

Week 2: Recent Past Climate Change

·         Last 2 million years are called quaterny period.

·        These period of time has seen some big climate change.

·         Over the last 2.6 billion years climate has been affected by many factors of forces.

·         On long time scales of several thousands of years,  climate change is highly predictable because of the way the earth moves around the sun. This is due to the angle and axis of the earth on its orbit around the sun. Variations in the shape of the earth’s orbit and amount of solar radiation received are down to three factors:  Eccentricity (100,000 years wear an almost circular orbit changes into a more elliptical orbit. When circular distribution of energy is equal throughout the year, when elliptical the earth is slightly closer to the sun sometimes, so it receives more energy at that time of the year. ), Obliquity (41,000 years where the earth’s axis tilt varies between 21.5 and 24.5 degree, this also changes the amount of solar radiation on the plane, greater tilt means more insulation at the polls during summer season), Precession (23,000 years where the earth’s axis wobbles like a spinning top, as it wobbles the timing of the seas sons changes, 11,000 years ago the northern hemisphere was tilted towards the sun at the same time as when the earth is at its closest point to the sun, this meant there was a greater difference between summer insulation and winter insulation, causing much more seasonal climates.)

·         The causes of climate change are much more unpredictable on a scale of 100 of years.

·         We can’t predict natural variability precisely because of earth system feedbacks but also other short term inferences on climate variability.

·         Unpredictable variations in climate change such as variations of the energy that the sun puts out, called solar-variability, volcanoes also play a role and a reason for short term highly unprediable changes in weather and climate, effect global temperatures, volcanoes cause cooling, areoles from the volcano reflect sun back into space cooling the planet,.

·         Climate change records from the last 100-150 years natural forcing factors fail to explain what is happening to climate change.

·         If we look at the hockey stick graph, it shows us that temperature has increased dramatically over the last 100-150 years. In a way that can’t be explain by natural forces. Co2 is the big new player in this story