diff --git a/agenda/types.py b/agenda/types.py
index 37fbe06..4f9d273 100644
--- a/agenda/types.py
+++ b/agenda/types.py
@@ -204,6 +204,10 @@ class Trip:
             else None
         )
 
+    def total_co2_kg(self) -> float | None:
+        """Total CO₂ for trip."""
+        return sum(float(t.get("co2_kg", 0)) for t in self.travel)
+
     @property
     def flights(self) -> list[StrDict]:
         """Flights."""
diff --git a/templates/macros.html b/templates/macros.html
index a7b67a7..9a7b068 100644
--- a/templates/macros.html
+++ b/templates/macros.html
@@ -113,7 +113,7 @@
       {% endif %}
     {% endif %}
   </div>
-  {% for i in range(8) %}
+  {% for i in range(9) %}
     <div class="grid-item"></div>
   {% endfor %}
 
@@ -143,6 +143,7 @@
         {{ "{:,.0f} km / {:,.0f} miles".format(item.distance, item.distance / 1.60934) }}
       {% endif %}
     </div>
+    <div class="grid-item text-end">{{ "{:,.1f}".format(item.co2_kg) }} kg</div>
   {% endfor %}
 {% endmacro %}
 
@@ -306,6 +307,7 @@
 {% macro trip_item(trip) %}
   {% set distances_by_transport_type = trip.distances_by_transport_type() %}
   {% set total_distance = trip.total_distance() %}
+  {% set total_co2_kg = trip.total_co2_kg() %}
   {% set end = trip.end %}
   <div class="border border-2 rounded mb-2 p-2">
     <h3>
@@ -335,6 +337,7 @@
       </div>
     {% endif %}
 
+
     {% if distances_by_transport_type %}
       {% for transport_type, distance in distances_by_transport_type %}
         <div>
@@ -344,6 +347,10 @@
       {% endfor %}
     {% endif %}
 
+    {% if total_co2_kg %}
+      <div>Total CO₂: {{ "{:,.1f}".format(total_co2_kg) }} kg</div>
+    {% endif %}
+
     {{ conference_list(trip) }}
 
     {% for day, elements in trip.elements_grouped_by_day() %}
@@ -381,6 +388,7 @@
                   <span class="text-nowrap"><strong>duration:</strong> {{ e.detail.duration }}</span>
                 {% endif %}
                 {# <pre>{{ e.detail | pprint }}</pre> #}
+      <span class="text-nowrap"><strong>CO₂:</strong> {{ "{:,.1f}".format(e.detail.co2_kg) }} kg</span>
               {% endif %}
               {% if e.detail.distance %}
                 <span class="text-nowrap"><strong>distance:</strong> {{ format_distance(e.detail.distance) }}</span>
diff --git a/templates/travel.html b/templates/travel.html
index 06d1d4e..ebb937b 100644
--- a/templates/travel.html
+++ b/templates/travel.html
@@ -3,7 +3,7 @@
 
 {% block title %}Travel - Edward Betts{% endblock %}
 
-{% set flight_column_count = 10 %}
+{% set flight_column_count = 11 %}
 {% set column_count = 10 %}
 
 {% block style %}
@@ -47,6 +47,7 @@
       <div class="grid-item">flight</div>
       <div class="grid-item">tracking</div>
       <div class="grid-item">distance</div>
+      <div class="grid-item">CO₂ (kg)</div>
 
     {% for item in flights %}
       {{ flight_booking_row(item) }}
diff --git a/templates/trip/list.html b/templates/trip/list.html
index afb5c2c..2e9fe5a 100644
--- a/templates/trip/list.html
+++ b/templates/trip/list.html
@@ -62,6 +62,7 @@
         distance: {{format_distance(distance) }}
       </div>
     {% endfor %}
+    <div>Total CO₂: {{ "{:,.1f}".format(total_co2_kg / 1000.0) }} tonnes</div>
 
     {% for trip in items %}
       {{ trip_item(trip) }}
diff --git a/update.py b/update.py
index 30b65a7..2c94e6a 100755
--- a/update.py
+++ b/update.py
@@ -8,7 +8,7 @@ import typing
 from datetime import date, datetime
 from time import time
 
-import deepdiff  # type: ignore
+import deepdiff
 import flask
 import requests
 import yaml
diff --git a/web_view.py b/web_view.py
index 70c48dd..62222be 100755
--- a/web_view.py
+++ b/web_view.py
@@ -404,13 +404,17 @@ def calc_total_distance(trips: list[Trip]) -> float:
     """Total distance for trips."""
     total = 0.0
     for item in trips:
-        dist = item.total_distance()
-        if dist:
+        if dist := item.total_distance():
             total += dist
 
     return total
 
 
+def calc_total_co2_kg(trips: list[Trip]) -> float:
+    """Total CO₂ for trips."""
+    return sum(item.total_co2_kg() for item in trips)
+
+
 def sum_distances_by_transport_type(trips: list[Trip]) -> list[tuple[str, float]]:
     """Sum distances by transport type."""
     distances_by_transport_type: defaultdict[str, float] = defaultdict(float)
@@ -443,6 +447,7 @@ def trip_past_list() -> str:
         format_list_with_ampersand=format_list_with_ampersand,
         fx_rate=agenda.fx.get_rates(app.config),
         total_distance=calc_total_distance(past),
+        total_co2_kg=calc_total_co2_kg(past),
         distances_by_transport_type=sum_distances_by_transport_type(past),
     )
 
@@ -475,6 +480,7 @@ def trip_future_list() -> str:
         format_list_with_ampersand=format_list_with_ampersand,
         fx_rate=agenda.fx.get_rates(app.config),
         total_distance=calc_total_distance(current + future),
+        total_co2_kg=calc_total_co2_kg(current + future),
         distances_by_transport_type=sum_distances_by_transport_type(current + future),
     )