20,000 years of Earth’s temperature reconstructed
The climate has always changed. This is true, but omits one very important factor of Earths climatic history: how long it takes for the climate to change. The Forever Project recast Earths temperature back to 20,050 BCE using data from climate models, estimates reconstructed from ice cores, and recorded observations, to compare the temperature to the 1961-1990 average. Data reporter Digital Designer Colder Warmer Our story starts 22,000 years ago... ... when Earth was a much colder planet than the one we inhabit now. Temperatures were about 3.5 degrees cooler than the 1961-1990 average, according to reconstructions from ice cores. That temperature difference caused Earth's landscape to be vastly different. New Zealand was a single island. Most of Europe was under ice... ... while ice caps extended over all of Canada and parts of northern the United States. This is the period of time historians call pre-history, before humans left written records. Not much... ... happened... ... during this time. (As far as we know) After migrating into the continent by traversing the Bering land bridge, people rapidly spread across both North and South America. Migration throughout the American continent, including the dates and the routes travelled, are still subject to ongoing research and discussion. Academics currently debate whether the migration south occured via land or water , with the latter hypothesis gaining prominence more recently . Humans spread over the Americas But the planet had slowly started to warm. Mostly due to small shifts in Earth's orbit and tilt. Seven thousand years since our timeline began... ... Earth's temperature rose by about 1 degree. Dogs domesticated Charred food remains from Shubayqa 1, an archaeological site in Jordan, infer the production of bread-like products. It is believed ancestors of domesticated crops such as wild einkorn wheat, barley and oats collected by hunter-gatherer Natufian people, were prepared over fire for consumption. Bread-making And sea-levels followed suit... ... possibly causing a cooling period dubbed the Younger Dryas But this colder era did not last long. Temperatures started to rise again. The switch from hunter-gatherer to agricultural societies led to a radical change from nomadism to sedentism. While at different paces, agriculture emerged independently across 11 main regions in the world. The first signs of crops being cultivated were in the Levant (modern-day Middle East), a region closely connected to evolution of human civilisation. Humans settle For a couple of millennia, we've been in what is called the Holocene. This is the epoch when humanity flourished... The Bering land bridge, once a path used by the humans who first reached the Americas, was inundated by the rising sea level. It now separates Siberia from Alaska. At its peak, the bridge was 1000 km wide in the north-south direction, larger than New Zealand's South Island (840 km). Bering bridge closed ... under ideal climate and... ... temperatures that kept steadily rising over millennia. Paleoclimatologists believe this period to have been slightly warmer than the 20th century average, peaking at around 8000 BCE. The warmer conditions would last many millennia. The Climate Optimum Research suggests the domestication of cats started with a "mutually beneficial" relationship between felines and human farmers in need of pest control. With crops and other agricultural products attracting rodents, cats started inhabitating human settlements in search of their prey. Later societies such as the Egyptian would worship the animals which may have contributed to how they behave today . Cats domesticated Freed from the cold of the past, humanity started creating... Evidence of an early mnemonic proto-writing system dating to this period was found in carved tortoise shells in Jiahu, China. The system was limited to a range of symbols. This is why it differs from a true writing system that records the writer's languages fully. A pre-writing system ... while oceans reached modern levels. Copper smelting was independently invented in different parts of the globe. The first evidence of copper smelting comes from modern-day Serbia around 5500 BCE. Because of its lower melting point, copper naturally became one of the first metals humans consistently worked, especially for weaponry. Copper smelting The wheel During these millennia, the temperature was less than 0.5 C above the 20th century average. Via the Balkans, migrants spread from most of Europe to the Indian peninsula. The languages they carried with them would give rise to some of the most spoken to this day, including English, Russian, German, and the modern languages rooted in Latin. European migrations A lot more is known about human activity during these times because humans started to keep records. The Botai, from modern-day Kazakhstan, were likely the first to domesticate horses, about a millennium before the previously accepted consensus of horse domestication, although DNA research suggests the animals were domesticated independently in Europe. The animals were used for transport, haulage, and meat, and took a central role in Botai culture , possibly contributing to the spread of Indo-European languages through the continent. Horses tamed Archaeologists found evidence of coal used as a source of power at a house site in the Shaanxi Province in China. dated around 3500 BCE. It is believed the people of northern and western China were the first to consistently use coal during its Bronze Age, between 2200 and 1900 BCE, in areas where near-surface coal was easily found. First evidence of coal usage Writing created Thousands of years before te reo developed in New Zealand, the Lapita people spoke the ancestral language known as proto-oceanic that would evolve into the Maori language. Before reaching Aotearoa, it expanded and developed throughout the Pacific , also originating other Polynesian languages such as Tahitian, Hawaiian, and Rapa Nui. Oceanic languages Candles used for light Temperature started to trend towards the 1961-90 average. The Babylonians largely expanded their empire during the 2nd century BCE under king Hammurabi. The ruins of the capital city Babylonia are today located 90 km south of Baghdad, Iraq. During this period, a sesame oil market for lighting fuel arose in the area now encompassing Iraq and Syria. Babylonian empire Pacific expansion The Chinese script developed over time from the mnemonic symbols used by people in the region into a logographic system for writing. By the second century BCE, it had over 2500 characters. Modern Chinese has in excess of 7000 characters. It is a unique system for its uninterrupted lineage , and for much of the Common Era was the most used form of script in the world. The Chinese script was highly influential to the development of writing in the East , contributing to the creation of Korean, Vietnamese, and Japanese writing. Chinese script Although iron alone did not give any advantage over the bronze tools and weapons used previously, the discovery of steel, by mixing iron and carbon, represented a technological leap. Steel not only changed warfare but also agriculture, while iron made its way into art. The Iron Age Troy siege Derived from the Phoenician alphabet, the Greek alphabet was the first to introduce distinct symbols to represent vowels and consonants. About a century after it emerged, the Greek system would give birth to the Latin script, a direct ascendant of the alphabet we use in modern times. Greek alphabet Divided in self-governing cities, Greece became an emerging mercantile region. The political and demographic organisation during this time of urbanisation gave rise to the "polis", a central concept of the Classical Period in Greece, some centuries later, when art, science, literature, and philosophy flourished. To this day, the Western democracies and culture are undeniably influenced by this era. Ancient Greece According to legend, two brothers raised by a "she-wolf" created the city on the margins of the Tiber river in the 8th century BCE. Archaeological evidence points to a settlement in the area dating as far back as the 10th century. The Romans would become a power of continental proportions, deeply influencing Western culture. Rome Mayan and Aztec civilisations in Central America developed writing systems of different complexities. The Mayan script is the only one that has been substantially deciphered , while there's still evolving research over whether the Aztec had a complete writing system. Both scripts were logographic, making use of symbols to represent words, augmented by syllabic signs. Mayan and Aztec writing Judaism derived from a polytheistic religion practised by the Israelites of the 7th century BCE. It is believed to be one of the first religions to have established itself as monotheistic the belief in one god. Judaism is the first of the Abrahamic religions, the branch that also gave rise to Christianity, in the 1st century CE, and Islam, in the 7th century CE. Judaism Euclidian geometry The Roman Empire The Hatepe eruption was the last explosion at Lake Taupo's caldera. The sequence of events on the northeastern side of today's lake buried the entire country in at least 1cm of ash. It was the most violent known volcanic eruption of the last 5000 years . NZ under 1cm of ash Under Emperor Constantine, Christianty was adopted as the official religion of the Roman Empire. Despite their increasing number within Roman territory, Christians were still persecuted for their faith before this. As a matter of scholarly debate, the adoption of Christianity by Rome is viewed as political manoeuvering , but with everlasting consequences. In its many forms today, Christianity is the most practised religion in the world. Christianity expansion The political end of the Roman Empire marks, for historians, the end of antiquity and the start of medieval times. This part of history is outlined by large counterurbanisation and population decline. Rome falls The Common Era, or the last 2000 years, has been colder than the 20th and 21st centuries. The earliest evidence of human presence in the Southern Cook Islands has been dated to around AD 1000. Cook Islands The Viking Era was marked by raiding and colonising, reaching as far west as the Americas. The people from Scandinavia were the first Europeans to reach the American continent, roughly half a century before the Spanish-sponsored expeditions of Columbus. Vikings From roughly 1300 to 1850, the Northern Hemisphere went through a minor cooling period that the geologist Francois Matthes named the Little Ice Age. Technically, it was not an Ice Age. According to the 3rd IPCC Assessment , it is better described as independent regional climate changes. It potentially affected New Zealand, where glaciers advanced during these centuries. The Little "Ice Age" New Zealand settled Less than two centuries after the first people settled in New Zealand, hunting drove the Moa bird to extinction . Isolated from the rest of the world, New Zealand's ecosystems did not have evolutionary mecanisms to cope with newly introduced predators like humans. Moas extinct Dutch explorer Willem Janzsoon was the first known European to have reached Australia in modern times. During his 1605-06 expedition, he set foot on northern Queensland/Northern Australia. However, coins as old as the 10th century have been found in Northern Australia, indicating others may made it to Australia much earlier than Janzsoon. Europeans reach Australia Abel Tasman's Dutch expedition is recognised as the first record of Aotearoa indigenous people meeting with Europeans . After arriving at the west coast of the South Island, Tasman sailed north, also spotting the North Island before reaching Tonga and Fiji. Maori-European encounter A century after the Dutch navigator Tasman first reached New Zealand, the British ship Endeavour, helmed by James Cook, docked in Poverty Bay/Tairawhiti. Cook's voyage to the Southern Pacific in search of land was commissioned by the British Admiralty. Cook anchors in NZ William Murdock, a British engineer and inventor, used coal-gas illumination in his Cornwall home. Coal-gas illumination Te Tiriti signed A violent earthquake shook the nation on January 23, 1855. The magnitude 8.2 quake was centred in the Wairarapa and killed at least five people. 8.2 earthquake The first commercial application of electricity in New Zealand was a hydro-powered station in 1886, suppyling electricity the Bullendale gold mine in Otago. Two years later, the first area to officially supply electricity to the public in New Zealand was Reefton, on August 4, 1888. The world's first coal-powered plant was built by Thomas Edison, in 1882, in New York. Electricity in NZ Kiwi soldiers fought - and died - in the failed Gallipoli campaign of World War One. Almost 3000 New Zealand soldiers were killed in the months-long battle in Turkey. Gallipoli Tenzing Norgay and Edmund Hillary reached the summit of Everest on May 29 1953. Everest conquered The February 22, 2011 Canterbury earthquake hit with a 7.1 magnitude , leaving significant destruction behind and 185 dead. Christchurch and Lyttleton, the epicenter of the earthquake, were among the most affected areas . Christchurch earthquake This story incorrectly referred to the strait between Tasmania and Victoria in Australia. It was amended at 10:30 on June 23 to reflect that the Bass Strait, not the Torres Strait, separates the two Australian states. Together, we can keep it that way. Like you, we want a better future for all New Zealanders. We want to know how the Government plans to get to zero carbon, and how the Climate Change Commission's advice will be activated. Our specialist climate desk is committed to covering this global crisis with a unique mix of rigour, reality and resolve. We're asking for your support to ensure this essential work remains accessible to everyone. If you're concerned about the climate, please become a Stuff supporter today. Your contribution will help power our climate change reporting, and support our mission to make Aotearoa a better place, together.