global change bio

Global Change Biology

Interaction between biological systems and environmental changes affecting a substantial part of the globe

Global Change Biology scope

Includes adaptations and evolutionary processes responding to global change drivers

Five drivers of global change

Climate change habitat loss and fragmentation invasive species pollution overexploitation of natural resources

Anthropocene definition

Proposed geological epoch defined by significant human impact on Earth systems

Anthropocene origin

Concept introduced by Paul Crutzen in 2000

Anthropogenic meaning

Human influenced

Anthropocene start (Crutzen & Stoermer)

Around 1750 with first atmospheric impacts

Alternative Anthropocene start dates

1610 and 1964 proposed by Maslin & Lewis

Holocene definition

Previous geological epoch beginning 10000-12000 years ago

Anthropocene characteristics

Human-driven changes to biophysical systems of the planet

Modern Anthropocene marker

~1950 marked by radioactive elements from nuclear tests

Other Anthropocene markers

Plastic pollution soot chicken bone proliferation

Arguments for Anthropocene

40% oil used 50% land transformed by direct human action with consequences for biodiversity

fixed synthetically more nitrogen for fertilisers and through fossil fuel
combustion than is fixed naturally in all terrestrial ecosystems
appropriated more than half of all accessible freshwater for human
purposes

Drivers of global change

Human population needs, the amount of people have exploded from 8 billion

Population vs consumption trends

Population doubled grain tripled energy quadrupled economy quintupled

North America and Europe consume more energy per person despite smaller population

Consumption inequality

Increases not uniform globally

Climate change definition

Earth warming due to greenhouse gas concentrations

Greenhouse effect

Atmospheric gases trap radiant heat

Greenhouse gases

CO2 methane nitrous oxide chlorofluorocarbons

Anthropogenic climate change

Increase in greenhouse gases post-industrialisation

Pre-industrial CO2 levels

~280 ppm ,

Current CO2 levels

Over 430 ppm

Temperature increase

~1.5°C above pre-industrial levels in 2024

Climate lag effect

Temperatures continue rising even if emissions stop due to gas persistence eg CO2 takes more time whereas methane takes shorter amounts of of retention time

Biodiversity responses to climate change

Move e.g species want to get cooler they move northward or upward- we have less cold winters which kills less diseases

adapt, or die

Adapt: Phenology definition

Study of timing of life history events

Phenological change example

Earlier flowering and butterfly emergence 15 days earlier

Phenological mismatch

Different species respond differently causing ecological disruption e.g butterflies emerge early but does the food they feed on?

can species adapt in time?

Climate change rates exceed evolutionary adaptation rates

no evidence of physiology changes at the rate of climate change

Habitat fragmentation definition

Large habitat split into smaller isolated patches

Habitat loss outcome

Usually results in fragmentation

Fragmentation components

Patch number patch size patch isolation patch shape

Island Biogeography Theory

Explains species richness based on area and isolation

expected number of species lies at the intersection of the colonisation and extinction curves\

larger island will have greater rates of immigration as animal will be likely to see it/hit it

large island= more people but less genetic diversity and stochastic events

Species equilibrium point

Intersection of colonisation and extinction rates

Fragmentation impacts

Smaller areas support fewer species

Small population risks

Competition stochastic loss inbreeding

Invasive species definition

Species introduced outside native range that establish and spread

A species that arrives (often with human assistance) in a habitat it had not
previously occupied, then establishes a population and spreads autonomously’

Introduction mechanism

Often human assisted

Island vulnerability

High proportion of invasive species

Example Hawaii invasives

50% plants 25% insects 40% birds most freshwater fish

Example Florida invasives

27% plants 8% insects 5% birds 24% freshwater fish

Invasive species ecosystem impact

Modify ecosystems by overgrowing or shading natives

Water hyacinth example

Covers water bodies reduces oxygen affects aquatic life

Resource competition example

Grey squirrels outcompete red squirrels

Predation impact

Introduced predators cause extinctions especially on islands

Rat impact

Responsible for extinction of at least 37 island bird species

Enemy Release Hypothesis

Introduced species escape natural enemies increasing success

ERH mechanism

Energy reallocated from defence to growth and reproduction

Overexploitation definition

Harvest rate exceeds natural replacement rate

Fishery sustainability decline

Unsustainable stocks increased from 10% in 1974 to 35.4% in 2019

Marine exploitation level

~90% of fisheries fully or overexploited

Fishing down the food web

Shift from large predators to smaller species after depletion

Cause of fishing down

Reduced populations of large fish

Consequence

Collapse of marine ecosystems

Tragedy of the commons

Individuals acting in self-interest deplete shared resources

Concept origin

Garrett Hardin 1968

Pollution definition

Introduction of harmful materials or energy into environment

Pollution types

Air water land contamination

Noise pollution effect

Alters animal behaviour such as predator response

One Health concept

Integrated approach linking human animal and ecosystem health

Genetics in global change

Study of gene flow and epigenetic responses under environmental stress

Neuroscience in global change

Effects of pollutants and sensory disruption on neural systems

Physiology in global change

Thermal tolerance and pharmaceutical pollution effects

Zoology in global change

Ecosystem resilience species redistribution conservation

Microbiology in global change

Pathogen range shifts and microbiome disruption

Biochemistry in global change

Metabolic adaptation and biochemical cycles in climate feedbacks

Summary global change

Unprecedented environmental change defining possible new epoch

Main drivers summary

Climate change habitat fragmentation invasive species overexploitation pollution

Impact on biodiversity

Declines in species and altered behaviour and distribution

Importance of study

Critical for all biological fields and future adaptation strategies

Future outlook

Mitigation and adaptation require interdisciplinary collaboration