torsdag 18. januar 2018



MYTE #2 
Jeg har da ikke feber, jeg fryser jo sånn!

Even as climate warms, we will always have winter (cold weather, snowstorms, blizzards). Winter is related to how the Earth is tilted on its axis as it moves around the Sun.

Climate change is the long term trends, measured over decades or more, and those long term trends show that the globe is still warming. 
"The difference between weather and climate is a measure of time. Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere "behaves" over relatively long periods of time. When we talk about climate change, we talk about changes in long-term averages of daily weather"

Det er lett å blande sammen nylige værhendelser med langsiktige klimatrender, og det er vanskelig å forstå forskjellen mellom vær og klima.[...] For å finne klimatrender, så må man se på hvordan været endrer seg over et lengre tidsrom. Daniel Bailey sitt bilde.
Gjennom å se på høye og lave temperaturer fra de siste tiår, så ser vi at nye varmerekorder inntreffer nesten dobbelt så ofte som nye kulderekorder. LES MER OM KALDE VINTRE OG GLOBAL OPPVARMING HER.

Climate sceptics often claim that recent icy winters show that global warming is not happening. New research suggests the opposite is true: As the ice melts it exposes open water which, being very much darker, absorbs more heat. The warmer water then warms the air above it which in turn, weakens the jet stream, the high level river of air which does much to determine the weather. As the jet stream slows down it meanders more, causing weather systems to get stuck in place with a “blocking pattern” that pulls cold, Arctic air down over Europe and northern Asia for long periods at a time. And, sure enough they say, recent cold winters have occurred in years when the amount of Arctic sea ice was especially low.
‘It’s too cold to snow’ — if it’s very cold, there is too little water vapor in the air to support a very heavy snowfall, and if it’s too warm, most of the precipitation will fall as rain.”[...] “Warmer air can contain more water vapor than cooler air. Global analyses show that the amount of water vapor in the atmosphere has in fact increased due to human-caused warming…. This extra moisture is available to storm systems, resulting in heavier rainfalls. Climate change also alters characteristics of the atmosphere that affect weather patterns and storms.”
Wet and dry extremes across the world will become more marked as the planet heats up, evidence from past climates shows.
The answer to the oft-asked question of whether an event is caused by climate change is that it is the wrong question. All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be. Framing the way to relate climate extremes to climate change.
Colder Winters Don't Mean Global Warming Isn't Happening
In recent decades, the Arctic has experienced more than its fair share of warming thanks to a phenomenon called Arctic amplification. A loss of sea ice, hotter ocean currents, and increased atmospheric water vapour mean temperatures have risen twice as fast around northern latitudes. These changes have also been associated with harsher winters much further south, a knock-on effect that often confuses people who assume global warming means we can all ditch our mittens. This new research has shown how above average temperatures in the Arctic lead to lower plant growth and decreased uptake of carbon dioxide in North American ecosystems.
How Does Changing Climate Bring More Extreme Events? 
The editors of a new book describe how and why weather and climate phenomena are intensifying with climate change.
Weather Patterns Are Getting Stuck as Climate Changes Affect the Jet Stream
Due to the nature of their work, climate scientists know more than the rest of us — but even they don't always agree about the ways in which climate change will affect weather in specific places. In 2012, a controversial study challenged previously accepted ideas about the mechanisms through which climate change will affect our weather: Warmer temperatures will result in more heat waves, hotter summers will bring worse droughts, the warmer atmosphere will hold more water, resulting in heavier precipitation and flooding. All of this might be true, but this study suggested that something else might be happening as well — that the relatively predictable flow of Earth's weather is changing. Due to alterations in the behavior of the jet stream, especially in the middle latitudes, weather patterns are getting "stuck" in place for longer periods, intensifying the on-the-ground effects, resulting in severe droughts, flooding and intense heat waves. 
Polar Vortex: How the Jet Stream and Climate Change Bring on Cold Snaps
Global warming plays a role in blasts of bitter cold weather. The reason: It influences the jet stream.
Eller som wikipedia forklarer : Den nordlige polare jetstrømmen ligger over de tett befolkede områdene i Europa, Nord-Amerika og Øst-Asia, og de viktige havene mellom disse verdensdelene. Lavtrykk med tilhørende nedbør og vind dannes ved polarfronten. Posisjonen til jetstrømmen er derfor avgjørende for været i disse områdene, og kunnskap om jetstrømmen er nødvendig for nøyaktig værvarsling. Avvik fra normal jetstrøm fører til uvanlige værsituasjoner. Sommeren 2007 lå jetstrømmen lenger sør enn vanlig. Dette førte til mye nedbør og store oversvømmelser i blant annet Storbritannia og Sør-Norge. Nord-Norge hadde derimot uvanlig varmt og tørt vær. Temperaturforskjellen driver jetstrømmen, og når forskjellen blir mindre kan jetstrømmen svekkes og buktningene bli større.

Rachel Molloy sitt bilde.
Scientists stunned by massive snowfall increases among Alaska’s highest peaks

Climate change increases the volume of precipitation, because a warmer atmosphere holds more water vapor. But it isn’t supposed to increase it this much. The researchers attribute part of the snowfall increase to the atmosphere’s retaining more water vapor, but also say that the warming up of the tropical Pacific Ocean changed atmospheric patterns, leading more storms to track across Alaska — thus accounting for the one-two punch.
En lokal kaldværsdag har ingenting å gjøre med den langsiktige trenden bestående av en økende global temperatur.
Global warming is not the end of freezing cold winters, its a shift towards more record lows than record highs.

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