How are humans causing changes in ecosystems and the possible effects they are causing?

Answer 1

Well there are the obvious and the not so obvious problems. We have fundamentally changed the face of the earth. Basically, there are whole categories of ways that we have changed the world through building projects, exploration, manufacturing and transport, domestication, agriculture, mining, and even the content of our atmosphere. The only other organisms that have so fundamentally changed the way the ecosystems of the world work are corals, algae, and other foundational species.

Let's start with the oldest and work our way up, simply, or this will be an entire encyclopedia. Agriculture and domestication. We have terraformed whole continents in our persuit of the support of those species which we have decided are tasty and useful. We have displaced or eradicated thousands of species to make room for our farms. The Rocy Mountain Locust, for example, was completely eradicated in the last century. we peeled off an entire ecosystem's worth of native grasses to plant crops, and then we almost lost that in the dust bowl before we improved our ag practice. In Austrailia, they pulled up trees, and then discovered that the trees were the only thing preventing the land from becomeing saltwater wastelands. They cut down virgin rainforest in Brazil, and then the land underneath is barren within a few short years, stripped by rain and erosion. We've been actively involved in agriculture for about 6000-10,000 years now.

And that's a lot of poo spread around. No seriously. Not only human poo has to be accounted for, we're also talking about all of our livestock too. Fertilizer and water diverted from aquifers and rivers can make citrus grow in the desert, but also makes dead zones in river deltas.

We have actively played a part in reducing the variation of this planet, not just in terms of plants, but animals. We preserved for many centuries, those which we desired, and those which we did not were destroyed without a thought. Save the dog, slay the wolf. Hunt the lynx, but spare the feral cat. We have also hunted to depletion animals that were foundational, Moas, for example, were tasty for the Maori, but when they disappeared due to hunting, so too did the Haast's Eagle. Our explorations have introduced diseases and zoonoses that have destroyed not merely indigenous human populations, but also the endemic species. We have introduced snakes to Guam which destryed the bird population, mice and rats, cane toads, feral cats, camels, and more to Australia and New Zaland, the current die off in frogs worldwide is caused in some part by a pathogen that we introduced inadvertantly. Zebra mussels and algae infest waterways, European starlings swarm over North America, Quaker Parrots chatter over Brooklyn, Boa Constrictors slither through the everglades, and opossums, once restricted to Virginia and appalachia, are now all over the US. The list of this kind of change simply goes on and on.

So then there is mining. No other species on earth has ever cut the tops from mountains and distributed the contents all over the world. Only corals and us make islands and reefs. We have dug up rare earths, poisoning the land around for miles. What we do with them causes even more trouble, and we're not just talking chernobyl and Tepco. We're talking waste. Millions upon millions of metric tons worth of waste that will never degrade, that simply sits out there, or is buried, or burned, everything from plastic bags to used computers, to spent nuclear material. Some of this winds up in the sea creating garbage patches that are bigger than whole countries.

OUr building projects create types of environments that have never been seen before. Our highways cut up ecosystems and our fences hamper migration routes. We have flooded valleys to create resevoirs. The Three Gorges dam even slowed rotation of the earth. We destroy forests and then build skyscrapers.

We are responsible for emissions that change the composition of our atmosphere. Only plants have caused such a huge impact on the content of our air.